Twilight is sunlight illumination produced by diffuse sky radiation when the Sun is below the horizon as sunlight from the upper atmosphere is scattered in a way that illuminates both the Earth's lower atmosphere and also the Earth's surface. Twilight also is any period when this illumination occurs.
89-471: [REDACTED] Look up gloaming in Wiktionary, the free dictionary. Gloaming may refer to: Twilight , the period after sunset and before the darkness of night The Gloaming , an Irish traditional music group The Gloaming (album) , their first album Gloaming (horse) (1915–1932), a Thoroughbred racehorse The Gloaming (TV series) ,
178-428: A numeronym . For example, "i18n" abbreviates " internationalization ", a computer-science term for adapting software for worldwide use; the "18" represents the 18 letters that come between the first and the last in "internationalization". Similarly, "localization" can be abbreviated "l10n"; " multilingualization " "m17n"; and " accessibility " "a11y". In addition to the use of a specific number replacing that many letters,
267-645: A single word ("television" or "transvestite", for instance), and is in general spelled without punctuation (except in the plural). Although "PS" stands for the single English word " postscript " or the Latin postscriptum , it is often spelled with periods ("P.S.") as if parsed as Latin post scriptum instead. The slash ('/', or solidus ) is sometimes used to separate the letters in an acronym, as in "N/A" ("not applicable, not available") and "c/o" ("care of"). Inconveniently long words used frequently in related contexts can be represented according to their letter count as
356-596: A 2019 Australian web TV series The Gloaming , the subtitle of Radiohead's album Hail to the Thief and the title of one of its tracks See also [ edit ] All pages with titles containing Gloaming In the Gloaming (disambiguation) " Roamin' in the Gloamin' " , a song by Harry Lauder Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with
445-543: A boon from Brahma that he could not be killed during day or night, neither by human nor animal, neither inside his house nor outside. Vishnu appeared in a half-man half-lion form (neither human nor animal), and ended Hiranyakashipu's life at twilight (neither day nor night) while he was placed in the threshold of his house (neither inside nor outside). Twilight is important in Islam as it determines when certain universally obligatory prayers are to be recited. Morning twilight
534-569: A defensive position. Astronomical twilight is defined as when the geometric center of the Sun is between 18° and 12° below the horizon. During astronomical twilight, the sky is dark enough to permit astronomical observation of point sources of light such as stars , except in regions with more intense skyglow due to light pollution , moonlight , auroras , and other sources of light. Some critical observations, such as of faint diffuse items such as nebulae and galaxies , may require observation beyond
623-680: A different meaning. Medical literature has been struggling to control the proliferation of acronyms, including efforts by the American Academy of Dermatology. Acronyms are often taught as mnemonic devices: for example the colors of the rainbow are ROY G. BIV (red, orange, yellow, green, blue, indigo, violet). They are also used as mental checklists: in aviation GUMPS stands for gas-undercarriage-mixture-propeller-seat belts. Other mnemonic acronyms include CAN SLIM in finance, PAVPANIC in English grammar, and PEMDAS in mathematics. It
712-404: A lower angle. The observer's earthly location will pass through the various twilight zones less directly, taking more time. Within the polar circles , twenty-four-hour daylight is encountered in summer, and in regions very close to the poles, twilight can last for weeks on the winter side of the equinoxes . Outside the polar circles, where the angular distance from the polar circle is less than
801-781: A medial decimal point . Particularly in British and Commonwealth English , all such punctuation marking acronyms and other capitalized abbreviations is now uncommon and considered either unnecessary or incorrect. The presence of all-capital letters is now thought sufficient to indicate the nature of the UK , the EU , and the UN . Forms such as the U.S.A. for "the United States of America " are now considered to indicate American or North American English . Even within those dialects, such punctuation
890-407: A period when the letters are pronounced individually, as in " K.G.B. ", but not when pronounced as a word, as in " NATO ". The logic of this style is that the pronunciation is reflected graphically by the punctuation scheme. When a multiple-letter abbreviation is formed from a single word, periods are in general not used, although they may be common in informal usage. "TV", for example, may stand for
979-415: A polar night: between about 72°34' and 78°34' north or south. Solar noon at astronomical twilight during a polar night: between about 78°34' and 84°34' north or south. Solar noon at night during a polar night: between approximately 84°34' and exactly 90° north or south. At latitudes greater than 81°25' North or South, as the Sun's angular elevation difference is less than 18 degrees, twilight can last for
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#17327976909211068-436: A single word, such as NATO (as distinct from B-B-C )" but adds later "In everyday use, acronym is often applied to abbreviations that are technically initialisms, since they are pronounced as separate letters." The Chicago Manual of Style acknowledges the complexity ("Furthermore, an acronym and initialism are occasionally combined (JPEG), and the line between initialism and acronym is not always clear") but still defines
1157-515: A twentieth-century phenomenon. Linguist David Wilton in Word Myths: Debunking Linguistic Urban Legends claims that "forming words from acronyms is a distinctly twentieth- (and now twenty-first-) century phenomenon. There is only one known pre-twentieth-century [English] word with an acronymic origin and it was in vogue for only a short time in 1886. The word is colinderies or colinda , an acronym for
1246-471: A word, an abbreviation is not an acronym." In contrast, some style guides do support it, whether explicitly or implicitly. The 1994 edition of Merriam-Webster's Dictionary of English Usage defends the usage on the basis of a claim that dictionaries do not make a distinction. The BuzzFeed style guide describes CBS and PBS as "acronyms ending in S". Acronymy, like retronymy , is a linguistic process that has existed throughout history but for which there
1335-433: Is a night with only civil twilight which lasts from sunset to sunrise. At the winter solstice within the polar circle, twilight can extend through solar noon at latitudes below 72.561° (72°33′43″) for civil twilight, 78.561° (78°33′43″) for nautical twilight, and 84.561° (84°33′43″) for astronomical twilight. Twilight on Mars is longer than on Earth, lasting for up to two hours before sunrise or after sunset. Dust high in
1424-488: Is a question about how to pluralize acronyms. Often a writer will add an 's' following an apostrophe, as in "PC's". However, Kate L. Turabian 's A Manual for Writers of Research Papers, Theses, and Dissertations , writing about style in academic writings, allows for an apostrophe to form plural acronyms "only when an abbreviation contains internal periods or both capital and lowercase letters". Turabian would therefore prefer "DVDs" and "URLs" but "Ph.D.'s". The style guides of
1513-721: Is becoming increasingly uncommon. Some style guides , such as that of the BBC , no longer require punctuation to show ellipsis ; some even proscribe it. Larry Trask , American author of The Penguin Guide to Punctuation , states categorically that, in British English , "this tiresome and unnecessary practice is now obsolete." Nevertheless, some influential style guides , many of them American , still require periods in certain instances. For example, The New York Times Manual of Style and Usage recommends following each segment with
1602-411: Is common for grammatical contractions (e.g. don't , y'all , and ain't ) and for contractions marking unusual pronunciations (e.g. a'ight , cap'n , and fo'c'sle for "all right", "captain", and "forecastle"). By the early twentieth century, it was standard to use a full stop/period/point , especially in the cases of initialisms and acronyms. Previously, especially for Latin abbreviations , this
1691-631: Is especially important for paper media, where no search utility is available to find the first use.) It also gives students a convenient review list to memorize the important acronyms introduced in a textbook chapter. Expansion at first use and abbreviation keys originated in the print era, but they are equally useful for electronic text . While acronyms provide convenience and succinctness for specialists, they often degenerate into confusing jargon . This may be intentional, to exclude readers without domain-specific knowledge. New acronyms may also confuse when they coincide with an already existing acronym having
1780-596: Is formed from the Greek roots akro- , meaning 'height, summit, or tip', and -nym , 'name'. This neoclassical compound appears to have originated in German , with attestations for the German form Akronym appearing as early as 1921. Citations in English date to a 1940 translation of a novel by the German writer Lion Feuchtwanger . It is an unsettled question in English lexicography and style guides whether it
1869-464: Is generally said as two letters, but IPsec for Internet Protocol Security is usually pronounced as / ˌ aɪ ˈ p iː s ɛ k / or / ˈ ɪ p s ɛ k / , along with variant capitalization like "IPSEC" and "Ipsec". Pronunciation may even vary within a single speaker's vocabulary, depending on narrow contexts. As an example, the database programming language SQL is usually said as three letters, but in reference to Microsoft's implementation
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#17327976909211958-446: Is its original meaning and in common use. Dictionary and style-guide editors dispute whether the term acronym can be legitimately applied to abbreviations which are not pronounced as words, and they do not agree on acronym spacing , casing , and punctuation . The phrase that the acronym stands for is called its expansion . The meaning of an acronym includes both its expansion and the meaning of its expansion. The word acronym
2047-550: Is legitimate to use the word acronym to describe forms that use initials but are not pronounced as a word. While there is plenty of evidence that acronym is used widely in this way, some sources do not acknowledge this usage, reserving the term acronym only for forms pronounced as a word, and using initialism or abbreviation for those that are not. Some sources acknowledge the usage, but vary in whether they criticize or forbid it, allow it without comment, or explicitly advocate it. Some mainstream English dictionaries from across
2136-459: Is not uncommon for acronyms to be cited in a kind of false etymology , called a folk etymology , for a word. Such etymologies persist in popular culture but have no factual basis in historical linguistics , and are examples of language-related urban legends . For example, " cop " is commonly cited as being derived, it is presumed, from "constable on patrol", and " posh " from " port outward, starboard home ". With some of these specious expansions,
2225-534: Is on June 21st , while the summer solstice in the Southern Hemisphere is on December 21st . In Arctic and Antarctic latitudes in wintertime, the polar night only rarely produces complete darkness for 24 hours each day. This can occur only at locations within about 5.5 degrees of latitude of the Pole, and there only on dates close to the winter solstice . At all other latitudes and dates,
2314-415: Is traditionally pronounced like the word sequel . In writing for a broad audience, the words of an acronym are typically written out in full at its first occurrence within a given text. Expansion At First Use (EAFU) benefits readers unfamiliar with the acronym. Another text aid is an abbreviation key which lists and expands all acronyms used, a reference for readers who skipped past the first use. (This
2403-467: Is treated as a safeguard against encroachment upon either. It can be considered a liminal time. For example, the twilight of Friday is reckoned as Sabbath eve, and that of Saturday as Sabbath day; and the same rule applies to festival days. Acronym An acronym is a type of abbreviation consisting of a phrase whose only pronounced elements are the initial letters or initial sounds of words inside that phrase. Acronyms are often spelled with
2492-488: Is when morning prayers ( Fajr ) are done, while evening twilight is the time for evening prayers ( Maghrib prayer ). Also during Ramadhan, the time for suhoor (morning meal before fasting) ends at morning twilight, while fasting ends after sunset. There is also an important discussion in Islamic jurisprudence between "true dawn" and " false dawn ". In Judaism, twilight is considered neither day nor night; consequently it
2581-516: The Colonial and Indian Exposition held in London in that year." However, although acronymic words seem not to have been employed in general vocabulary before the twentieth century (as Wilton points out), the concept of their formation is treated as effortlessly understood (and evidently not novel) in an Edgar Allan Poe story of the 1830s, " How to Write a Blackwood Article ", which includes
2670-623: The Modern Language Association and American Psychological Association prohibit apostrophes from being used to pluralize acronyms regardless of periods (so "compact discs" would be "CDs" or "C.D.s"), whereas The New York Times Manual of Style and Usage requires an apostrophe when pluralizing all abbreviations regardless of periods (preferring "PC's, TV's and VCR's"). Possessive plurals that also include apostrophes for mere pluralization and periods appear especially complex: for example, "the C.D.'s' labels" (the labels of
2759-539: The Restoration witticism arranging the names of some members of Charles II 's Committee for Foreign Affairs to produce the "CABAL" ministry . OK , a term of disputed origin, dates back at least to the early nineteenth century and is now used around the world. Acronyms are used most often to abbreviate names of organizations and long or frequently referenced terms. The armed forces and government agencies frequently employ acronyms; some well-known examples from
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2848-480: The "belief" that the etymology is acronymic has clearly been tongue-in-cheek among many citers, as with "gentlemen only, ladies forbidden" for " golf ", although many other (more credulous ) people have uncritically taken it for fact. Taboo words in particular commonly have such false etymologies: " shit " from "ship/store high in transit" or "special high-intensity training" and " fuck " from "for unlawful carnal knowledge", or "fornication under consent/command of
2937-463: The 160-character SMS limit, and to save time, acronyms such as "GF" ("girlfriend"), "LOL" ("laughing out loud"), and "DL" ("download" or "down low") have become popular. Some prescriptivists disdain texting acronyms and abbreviations as decreasing clarity, or as failure to use "pure" or "proper" English. Others point out that languages have always continually changed , and argue that acronyms should be embraced as inevitable, or as innovation that adapts
3026-461: The 18 letters between the initial "i" and the final "n"). Authors of expository writing will sometimes capitalize or otherwise distinctively format the initials of the expansion for pedagogical emphasis (for example, writing: "the onset of Congestive Heart Failure (CHF)" or "the onset of c ongestive h eart f ailure (CHF)"). Capitalization like this, however, conflicts with the convention of English orthography, which generally reserves capitals in
3115-466: The British press may render it "Nato"), but uses lower case in " Unicef " (from "United Nations International Children's Emergency Fund") because it is more than four letters, and to style it in caps might look ungainly (flirting with the appearance of "shouting capitals"). While abbreviations typically exclude the initials of short function words (such as "and", "or", "of", or "to"), this is not always
3204-529: The Earth, including the entire United Kingdom and other countries in northern Europe and even parts of central Europe . This also occurs in the Southern Hemisphere, but occurs on December 21. This type of twilight also occurs between one day and the next at latitudes within the polar circles shortly before and shortly after the period of midnight sun. The summer solstice in the Northern Hemisphere
3293-844: The English-speaking world affirm a sense of acronym which does not require being pronounced as a word. American English dictionaries such as Merriam-Webster , Dictionary.com's Random House Webster's Unabridged Dictionary and the American Heritage Dictionary as well as the British Oxford English Dictionary and the Australian Macquarie Dictionary all include a sense in their entries for acronym equating it with initialism , although The American Heritage Dictionary criticizes it with
3382-464: The Sun is below the horizon. Examples include when drivers of automobiles must turn on their headlights (called lighting-up time in the UK), when hunting is restricted, or when the crime of burglary is to be treated as nighttime burglary, which carries stiffer penalties in some jurisdictions. The period may affect when extra equipment, such as anti-collision lights, is required for aircraft to operate. In
3471-404: The Sun is beneath the horizon, the dimmer the sky (other factors such as atmospheric conditions being equal). When the Sun reaches 18° below the horizon, the illumination emanating from the sky is nearly zero, and evening twilight becomes nighttime . When the Sun approaches re-emergence, reaching 18° below the horizon, nighttime becomes morning twilight. Owing to its distinctive quality, primarily
3560-564: The U.S. Navy, is "COMCRUDESPAC", which stands for "commander, cruisers destroyers Pacific"; it is also seen as "ComCruDesPac". Inventors are encouraged to anticipate the formation of acronyms by making new terms "YABA-compatible" ("yet another bloody acronym"), meaning the term's acronym can be pronounced and is not an offensive word: "When choosing a new name, be sure it is 'YABA-compatible'." Acronym use has been further popularized by text messaging on mobile phones with short message service (SMS), and instant messenger (IM). To fit messages into
3649-686: The US, civil twilight for aviation is defined in Part 1.1 of the Federal Aviation Regulations (FARs) as the time listed in the American Air Almanac. Nautical twilight occurs when the geometric center of the Sun is between 12° and 6° below the horizon. After nautical dusk and before nautical dawn, sailors cannot navigate via the horizon at sea as they cannot clearly see the horizon. At nautical dawn and nautical dusk,
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3738-560: The United States are among the " alphabet agencies " (jokingly referred to as " alphabet soup ") created under the New Deal by Franklin D. Roosevelt (himself known as "FDR"). Business and industry also coin acronyms prolifically. The rapid advance of science and technology also drives the usage, as new inventions and concepts with multiword names create a demand for shorter, more pronounceable names. One representative example, from
3827-553: The absence of other illumination, during nautical twilight, the human eye may distinguish general outlines of ground objects but cannot participate in detailed outdoor operations. Nautical twilight has military considerations as well. The initialisms BMNT (begin morning nautical twilight, i.e. nautical dawn) and EENT (end evening nautical twilight, i.e. nautical dusk) are used and considered when planning military operations. A military unit may treat BMNT and EENT with heightened security, e.g. by "standing to", for which everyone assumes
3916-496: The absence of shadows and the appearance of objects silhouetted against the lit sky, twilight has long been popular with photographers and painters, who often refer to it as the blue hour , after the French expression l'heure bleue . By analogy with evening twilight, sometimes twilight is used metaphorically to imply that something is losing strength and approaching its end. For example, very old people may be said to be "in
4005-411: The acronym may use normal case rules, e.g. it would appear generally in lower case, but with an initial capital when starting a sentence or when in a title. Once knowledge of the words underlying such an acronym has faded from common recall, the acronym may be termed an anacronym . Examples of anacronyms are the words " scuba ", " radar ", and " laser ". The word "an acro nym" should not be confused with
4094-590: The adoption of acronyms was modern warfare, with its many highly technical terms. While there is no recorded use of military acronyms dating from the American Civil War (acronyms such as "ANV" for " Army of Northern Virginia " post-date the war itself), they became somewhat common in World War I , and by World War II they were widespread even in the slang of soldiers, who referred to themselves as G.I.s . The widespread, frequent use of acronyms across
4183-543: The angle which defines twilight (see above), twilight can continue through local midnight near the summer solstice . The precise position of the polar circles, and the regions where twilight can continue through local midnight, varies slightly from year to year with Earth's axial tilt . The lowest latitudes at which the various twilights can continue through local midnight are approximately 60.561° (60°33′43″) for civil twilight, 54.561° (54°33′43″) for nautical twilight and 48.561° (48°33′43″) for astronomical twilight. These are
4272-506: The apostrophe should be reserved for the possessive ("the TV's antenna"). In some languages, the convention of doubling the letters in the acronym is used to indicate plural words: for example, the Spanish EE.UU. , for Estados Unidos ('United States'). This old convention is still sometimes followed for a limited number of English abbreviations, such as SS. for Saints , pp. for
4361-473: The atmosphere scatters light to the night side of the planet. Similar twilights are seen on Earth following major volcanic eruptions . In Christian practice, " vigil " observances often occur during twilight on the evening before major feast days or holidays. For example, the Easter Vigil is held in the hours of darkness between sunset on Holy Saturday and sunrise on Easter Day – most commonly in
4450-1163: The case. Sometimes function words are included to make a pronounceable acronym, such as CORE ( Congress of Racial Equality ). Sometimes the letters representing these words are written in lower case, such as in the cases of "TfL" (" Transport for London ") and LotR ( The Lord of the Rings ); this usually occurs when the acronym represents a multi-word proper noun. Numbers (both cardinal and ordinal ) in names are often represented by digits rather than initial letters, as in "4GL" (" fourth generation language ") or "G77" (" Group of 77 "). Large numbers may use metric prefixes , as with " Y2K " for "Year 2000". Exceptions using initials for numbers include " TLA " ("three-letter acronym/abbreviation") and "GoF" (" Gang of Four "). Abbreviations using numbers for other purposes include repetitions, such as " A2DP " ("Advanced Audio Distribution Profile"), " W3C " ("World Wide Web Consortium"), and T3 ( Trends, Tips & Tools for Everyday Living ); pronunciation, such as " B2B " ("business to business"); and numeronyms , such as "i18n" ("internationalization"; "18" represents
4539-413: The compact discs). In some instances, however, an apostrophe may increase clarity: for example, if the final letter of an abbreviation is "S", as in "SOS's" (although abbreviations ending with S can also take "-es", e.g. "SOSes"), or when pluralizing an abbreviation that has periods. A particularly rich source of options arises when the plural of an acronym would normally be indicated in a word other than
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#17327976909214628-564: The contrived acronym "P.R.E.T.T.Y.B.L.U.E.B.A.T.C.H." The use of Latin and Neo-Latin terms in vernaculars has been pan-European and pre-dates modern English. Some examples of acronyms in this class are: The earliest example of a word derived from an acronym listed by the OED is "abjud" (now " abjad "), formed from the original first four letters of the Arabic alphabet in the late eighteenth century. Some acrostics pre-date this, however, such as
4717-438: The dictionary entries and style guide recommendations regarding the term acronym through the twentieth century did not explicitly acknowledge or support the expansive sense. The Merriam–Webster's Dictionary of English Usage from 1994 is one of the earliest publications to advocate for the expansive sense, and all the major dictionary editions that include a sense of acronym equating it with initialism were first published in
4806-526: The entire 24 hours. This occurs for one day at latitudes near 8°35’ from the Pole and extends up to several weeks the further toward the Pole one goes. This happens both near the North Pole and near the South Pole. The only permanent settlement to experience this condition is Alert, Nunavut , Canada, where it occurs from February 22–26, and again from October 15–19. The duration of twilight depends on
4895-496: The evening of Holy Saturday or midnight – and is the first celebration of Easter, days traditionally being considered to begin at sunset. Hinduism prescribes the observance of certain practices during twilight, a period generally called sandhya . The period is also called by the poetic form of gōdhūḷi in Sanskrit , literally 'cow dust', referring to the time cows returned from the fields after grazing, kicking up dust in
4984-664: The exclusive sense for acronym and its earliest citation was from 1943. In early December 2010, Duke University researcher Stephen Goranson published a citation for acronym to the American Dialect Society e-mail discussion list which refers to PGN being pronounced "pee-gee-enn", antedating English language usage of the word to 1940. Linguist Ben Zimmer then mentioned this citation in his December 16, 2010 " On Language " column about acronyms in The New York Times Magazine . By 2011,
5073-763: The final word if spelled out in full. A classic example is "Member of Parliament", which in plural is "Members of Parliament". It is possible then to abbreviate this as "M's P", which was fairly common in mid-twentieth-century Australian news writing (or similar ), and used by former Australian Prime Minister Ben Chifley . This usage is less common than forms with "s" at the end, such as "MPs", and may appear dated or pedantic. In common usage, therefore, "weapons of mass destruction" becomes "WMDs", "prisoners of war" becomes "POWs", and "runs batted in" becomes "RBIs". Abbreviations that come from single, rather than multiple, words – such as "TV" ("television") – are usually pluralized without apostrophes ("two TVs"); most writers feel that
5162-464: The first letter of acronyms, reserving all-caps styling for initialisms, writing the pronounced acronyms "Nato" and "Aids" in mixed case, but the initialisms "USA" and "FBI" in all caps. For example, this is the style used in The Guardian , and BBC News typically edits to this style (though its official style guide, dating from 2003, still recommends all-caps ). The logic of this style is that
5251-400: The horizon while the brightest stars and planets can appear. As observed from the Earth (see apparent magnitude ), sky-gazers know Venus , the brightest planet, as the "morning star" or "evening star" because they can see it during civil twilight. Civil twilight statutes typically denote a fixed period after sunset or before sunrise (most commonly 20–30 minutes) rather than how many degrees
5340-517: The horizon), nautical twilight, and astronomical twilight (farthest from the horizon). Civil twilight is the time when the geometric center of the Sun is between the horizon and 6° below the horizon. Civil twilight is the period when enough natural light remains so that artificial light in towns and cities is not needed. In the United States' military, the initialisms BMCT ( begin morning civil twilight , i.e., civil dawn) and EECT ( end evening civil twilight , i.e., civil dusk) are used to refer to
5429-512: The human eye finds it difficult, if not impossible, to discern traces of illumination near the sunset or sunrise point of the horizon ( first light after nautical dawn but before civil dawn and nightfall after civil dusk but before nautical dusk). Sailors can take reliable star sightings of well-known stars, during the stage of nautical twilight when they can distinguish a visible horizon for reference (i.e. after astronomic dawn or before astronomic dusk). Under good atmospheric conditions with
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#17327976909215518-456: The initial letter of each word in all caps with no punctuation . For some, an initialism or alphabetism , connotes this general meaning, and an acronym is a subset with a narrower definition: an initialism pronounced as a word rather than as a sequence of letters. In this sense, NASA / ˈ n æ s ə / is an acronym but USA / j uː ɛ s ˈ eɪ / is not. The broader sense of acronym , ignoring pronunciation,
5607-435: The king". In English, abbreviations have previously been marked by a wide variety of punctuation . Obsolete forms include using an overbar or colon to show the ellipsis of letters following the initial part. The forward slash is still common in many dialects for some fixed expressions—such as in w/ for "with" or A/C for " air conditioning "—while only infrequently being used to abbreviate new terms. The apostrophe
5696-500: The label "usage problem". However, many English language dictionaries, such as the Collins COBUILD Advanced Dictionary , Cambridge Advanced Learner's Dictionary , Macmillan Dictionary , Longman Dictionary of Contemporary English , New Oxford American Dictionary , Webster's New World Dictionary , and Lexico from Oxford University Press do not acknowledge such a sense. Most of
5785-836: The language to changing circumstances. In this view, the modern practice is just the "proper" English of the current generation of speakers, much like the earlier abbreviation of corporation names on ticker tape or newspapers. Exact pronunciation of "word acronyms" (those pronounced as words rather than sounded out as individual letters) often vary by speaker population. These may be regional, occupational, or generational differences, or simply personal preference. For instance, there have been decades of online debate about how to pronounce GIF ( / ɡ ɪ f / or / dʒ ɪ f / ) and BIOS ( / ˈ b aɪ oʊ s / , / ˈ b aɪ oʊ z / , or / ˈ b aɪ ɒ s / ). Similarly, some letter-by-letter initialisms may become word acronyms over time, especially in combining forms: IP for Internet Protocol
5874-431: The largest cities of their respective countries where the various twilights can continue through local solar midnight: Although Helsinki, Oslo, Stockholm, Tallinn, and Saint Petersburg also enter into nautical twilight after sunset, they do have noticeably lighter skies at night during the summer solstice than other locations mentioned in their category above, because they do not go far into nautical twilight. A white night
5963-413: The latitude and the time of the year. The apparent travel of the Sun occurs at the rate of 15 degrees per hour (360° per day), but sunrise and sunset happen typically at oblique angles to the horizon and the actual duration of any twilight period will be a function of that angle, being longer for more oblique angles. This angle of the Sun's motion with respect to the horizon changes with latitude as well as
6052-641: The limit of astronomical twilight. Theoretically, the faintest stars detectable by the naked eye (those of approximately the sixth magnitude) will become visible in the evening at astronomical dusk, and become invisible at astronomical dawn . Observers within about 48°34' of the Equator can view twilight twice each day on every date of the year between astronomical dawn , nautical dawn, or civil dawn, and sunrise as well as between sunset and civil dusk, nautical dusk, or astronomical dusk. This also occurs for most observers at higher latitudes on many dates throughout
6141-601: The month of the autumnal equinox and the month of vernal equinox between astronomical dawn, nautical dawn, or civil dawn, and sunrise as well as between sunset and civil dusk, nautical dusk, or astronomical dusk, i.e., from September 1 to March 31 of the following year in the Northern Hemisphere and from March 1 to September 30 in the Southern Hemisphere . The nighttime/twilight boundary solar midnight's latitude varies depending on
6230-485: The month: At latitudes greater than about 48°34' North or South, on dates near the summer solstice ( June 21 in the Northern Hemisphere or December 21 in the Southern Hemisphere), twilight can last from sunset to sunrise, since the Sun does not sink more than 18 degrees below the horizon, so complete darkness does not occur even at solar midnight. These latitudes include many densely populated regions of
6319-466: The more general "x" can be used to replace an unspecified number of letters. Examples include "Crxn" for "crystallization" and the series familiar to physicians for history , diagnosis , and treatment ("hx", "dx", "tx"). Terms relating to a command structure may also sometimes use this formatting, for example gold, silver, and bronze levels of command in UK policing being referred to as Gx, Sx, and Bx. There
6408-729: The plural of 'pages', or mss. for manuscripts . The most common capitalization scheme seen with acronyms is all-uppercase ( all caps ). Small caps are sometimes used to make the run of capital letters seem less jarring to the reader. For example, the style of some American publications, including the Atlantic Monthly and USA Today , is to use small caps for acronyms longer than three letters; thus "U.S." and " FDR " in normal caps, but " nato " in small caps. The acronyms " AD " and " BC " are often smallcapped as well, as in: "From 4004 bc to ad 525 ". Where an acronym has linguistically taken on an identity as regular word,
6497-504: The polar night includes a daily period of twilight, when the Sun is not far below the horizon. Around winter solstice, when the solar declination changes slowly, complete darkness lasts several weeks at the Pole itself, e.g., from May 11 to July 31 at Amundsen–Scott South Pole Station . North Pole has the experience of this from November 13 to January 29. Solar noon at civil twilight during a polar night: between about 67°24' and 72°34' north or south . Solar noon at nautical twilight during
6586-573: The poles, civil twilight can be as long as 2–3 weeks. In the Arctic and Antarctic regions, twilight (if there is any) can last for several hours. There is no astronomical twilight at the poles near the winter solstice (for about 74 days at the North Pole and about 80 days at the South Pole). As one gets closer to the Arctic and Antarctic circles, the Sun's disk moves toward the observer's horizon at
6675-425: The process. Many rituals, such as Sandhyavandanam and puja , are performed at the twilight hour. Consuming food is not advised during this time. According to some adherents, asuras are regarded to be active during these hours. One of the avatars of Vishnu , Narasimha , is closely associated with the twilight period. According to Hindu scriptures , an asura king, Hiranyakashipu , performed penance and obtained
6764-483: The pronunciation is reflected graphically by the capitalization scheme. However, it conflicts with conventional English usage of first-letter upper-casing as a marker of proper names in many cases; e.g. AIDS stands for acquired immuno-deficiency syndrome which is not a proper name, while Aids is in the style of one. Some style manuals also base the letters' case on their number. The New York Times , for example, keeps "NATO" in all capitals (while several guides in
6853-685: The publication of the 3rd edition of the Oxford English Dictionary added the expansive sense to its entry for acronym and included the 1940 citation. As the Oxford English Dictionary structures the senses in order of chronological development, it now gives the "initialism" sense first. English language usage and style guides which have entries for acronym generally criticize the usage that refers to forms that are not pronounceable words. Fowler's Dictionary of Modern English Usage says that acronym "denotes abbreviations formed from initial letters of other words and pronounced as
6942-470: The sides of railroad cars (e.g., "Richmond, Fredericksburg and Potomac Railroad" → "RF&P"); on the sides of barrels and crates; and on ticker tape and newspaper stock listings (e.g. American Telephone and Telegraph Company → AT&T). Some well-known commercial examples dating from the 1890s through 1920s include " Nabisco " ("National Biscuit Company"), " Esso " (from "S.O.", from " Standard Oil "), and " Sunoco " ("Sun Oil Company"). Another field for
7031-514: The start of morning civil twilight and the end of evening civil twilight, respectively. Civil dawn is preceded by morning nautical twilight and civil dusk is followed by evening nautical twilight. Under clear weather conditions, civil twilight approximates the limit at which solar illumination suffices for the human eye to clearly distinguish terrestrial objects. Enough illumination renders artificial sources unnecessary for most outdoor activities. At civil dawn and at civil dusk, sunlight clearly defines
7120-502: The terms as mutually exclusive. Other guides outright deny any legitimacy to the usage: Bryson's Dictionary of Troublesome Words says "Abbreviations that are not pronounced as words (IBM, ABC, NFL) are not acronyms; they are just abbreviations." Garner's Modern American Usage says "An acronym is made from the first letters or parts of a compound term. It's read or spoken as a single word, not letter by letter." The New York Times Manual of Style and Usage says "Unless pronounced as
7209-459: The time of year (affecting the angle of the Earth's axis with respect to the Sun). At Greenwich, England (51.5°N), the duration of civil twilight will vary from 33 minutes to 48 minutes, depending on the time of year. At the equator , civil twilight can last as little as 24 minutes. This is true because at low latitudes the Sun's apparent movement is perpendicular to the observer's horizon. But at
7298-452: The title Gloaming . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Gloaming&oldid=913372422 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Twilight The lower
7387-570: The twenty-first century. The trend among dictionary editors appears to be towards including a sense defining acronym as initialism : the Merriam-Webster's Collegiate Dictionary added such a sense in its 11th edition in 2003, and both the Oxford English Dictionary and The American Heritage Dictionary added such senses in their 2011 editions. The 1989 edition of the Oxford English Dictionary only included
7476-488: The twilight of their lives". The collateral adjective for twilight is crepuscular , which may be used to describe the behavior of animals that are most active during this period. Twilight occurs according to the solar elevation angle θ s , which is the position of the geometric center of the Sun relative to the horizon. There are three established and widely accepted subcategories of twilight: civil twilight (nearest
7565-536: The whole range of linguistic registers is relatively new in most languages, becoming increasingly evident since the mid-twentieth century. As literacy spread and technology produced a constant stream of new and complex terms, abbreviations became increasingly convenient. The Oxford English Dictionary ( OED ) records the first printed use of the word initialism as occurring in 1899, but it did not come into general use until 1965, well after acronym had become common. In English, acronyms pronounced as words may be
7654-425: The word " an achro nym ", which is a type of misnomer. Words derived from an acronym by affixing are typically expressed in mixed case, so the root acronym is clear. For example, "pre-WWII politics", "post-NATO world", " DNase ". In some cases a derived acronym may also be expressed in mixed case. For example, " messenger RNA " and " transfer RNA " become "mRNA" and "tRNA". Some publications choose to capitalize only
7743-457: The year, except those around the summer solstice. However, at latitudes closer than 8°35' (between 81°25’ and 90°) to either Pole, the Sun cannot rise above the horizon nor sink more than 18° below it on the same day on any date, so this example of twilight cannot occur because the angular difference between solar noon and solar midnight is less than 17°10’. Observers within 63°26' of the Equator can view twilight twice each day on every date between
7832-511: Was done with a full space between every full word (e.g. A. D. , i. e. , and e. g. for " Anno Domini ", " id est ", and " exempli gratia "). This even included punctuation after both Roman and Arabic numerals to indicate their use in place of the full names of each number (e.g. LII. or 52. in place of "fifty-two" and "1/4." or "1./4." to indicate "one-fourth"). Both conventions have fallen out of common use in all dialects of English, except in places where an Arabic decimal includes
7921-449: Was little to no naming , conscious attention, or systematic analysis until relatively recent times. Like retronymy, it became much more common in the twentieth century than it had formerly been. Ancient examples of acronymy (before the term "acronym" was invented) include the following: During the mid- to late nineteenth century, acronyms became a trend among American and European businessmen: abbreviating corporation names, such as on
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