flagとは 意味・読み方・使い方

発音

• (英国発音, 米国発音) IPA: /flæɡ/
• 韻: -æɡ, -eɪɡ

語源 1

From 中期英語 flag, flagge (“flag”), further etymology uncertain. Perhaps from or related to early 中期英語 flage (name for a baby's garment) and 古期英語 flagg, flacg (“cataplasm, poultice, plaster”). Or, perhaps ultimately imitative, or otherwise drawn from Proto-Germanic *flaką (“something flat”), from Proto-Indo-European *pleh₂- (“flat, broad, plain”), referring to the shape.

Germanic cognates include Saterland Frisian Flaage (“flag”), West Frisian flagge (“flag”), Dutch vlag (“flag”), German Flagge (“flag”), Swedish flagga (“flag”), Danish flag (“flag, ship's flag”). Compare also 中期英語 flacken (“to flutter, palpitate”), Swedish dialectal flage (“to flutter in the wind”), Old Norse flögra (“to flap about”). Akin to Old High German flogarōn (“to flutter”), Old High German flogezen (“to flutter, flicker”), 中期英語 flakeren (“to move quickly to and fro”), 古期英語 flacor (“fluttering, flying”). More at flack, flacker.

名詞

flag (countable and uncountable, plural flags)

1. A piece of cloth, often decorated with an emblem, used as a visual signal or symbol.
   • 2020 May 15, “Burning EU and other flags can now bring German jail term”, in BBC‎, archived from the original on 4 June 2025:

     The vote in the Bundestag (parliament) on Thursday makes defiling foreign flags equal to the crime of defiling the German flag. […] The new law also applies to acts of defilement besides burning, such as publicly ripping a flag up.

2. The design that could be placed on a flag, typically a rectangular graphic that is used to represent an entity (like a country, organisation or group of people) or an idea.

   The flag of France has three vertical stripes.

3. (nautical) A flag flown by a ship to show the presence on board of the admiral; the admiral himself, or his flagship.
4. (nautical, often used attributively) A signal flag.
5. The use of a flag, especially to indicate the start of a race or other event.
6. (computer science) A variable or memory location that stores a Boolean true-or-false, yes-or-no value, typically either recording the fact that a certain event has occurred or requesting that a certain optional action take place.
7. (computer science) In a command line interface, a command parameter requesting optional behavior or otherwise modifying the action of the command being invoked.
   • 2021, Angel Sola Orbaiceta, Hardcore Programming for Mechanical Engineers, pages 19–2:

     This will be used as a help message if the user passes in the --help flag, like so: […]

8. (aviation) A mechanical indicator that pops up to draw the pilot's attention to a problem or malfunction.
   • 1966, Barry J. Schiff, All about Flying: An Introduction to the World of Flying, page 72:

     I was shooting an IFR approach down the San Francisco slot, when all of a sudden the ILS flag popped up.

   • 1980, Paul Garrison, Flying VFR in marginal weather, page 139:

     […] and then the OFF flag popped up and the needle went dead.

9. (British, uncountable) The game of capture the flag.
10. (geometry) A sequence of faces of a given polytope, one of each dimension up to that of the polytope (formally, though in practice not always explicitly, including the null face and the polytope itself), such that each face in the sequence is part of the next-higher dimension face.
    • 1994, John Ratcliffe, Foundations of Hyperbolic Manifolds‎, page 230:

      A flag of P is a sequence (F₀, F₁, ..., F_m) of faces of P such that dim F_i = i for each i and F_i is a side of F_i+1 for each i < m. […] A regular polytope in X is a polytope P in X whose group of symmetries in <P> acts transitively on its flags.

    • 2002, Peter McMullen, Egon Schulte, Abstract Regular Polytopes, Encyclopedia of Mathematics and Its Applications 92, page 31:

      We call P (combinatorially) regular if its automorphism group Γ(P) is transitive on its flags.

    • 2006, Peter McMullen, Egon Schulte, “Regular and Chiral Polytopes in Low Dimensions”, in Harold Scott Macdonald Coxeter, Chandler Davis, Erich W. Ellers, editors, The Coxeter Legacy: Reflections and Projections, page 91:

      Roughly speaking, chiral polytopes have half as many possible automorphisms as have regular polytopes. More technically, the n-polytope P is chiral if it has two orbits of flags under its group Γ(P), with adjacent flags in different orbits.

11. (mathematics, linear algebra) A sequence of subspaces of a vector space, beginning with the null space and ending with the vector space itself, such that each member of the sequence (until the last) is a proper subspace of the next.
12. (television) A dark piece of material that can be mounted on a stand to block or shape the light.
    • 1999, Des Lyver, Graham Swainson, Basics of Video Lighting, page 103:

      At the other extreme, with limitless budgets all they have to do is dream up amazing lighting rigs to be constructed and operated by the huge team of gaffers and sparks, with their generators, discharge lights, flags, gobos and brutes.

    • 2012, John Jackman, Lighting for Digital Video and Television, page 86:

      Flags and other cutters allow the DP or gaffer to throw large controlled shadows on parts of the scene.

13. (UK, archaic, slang) An apron.
    • 1887, William Ernest Henley, Villon's Straight Tip to All Cross Coves:

      Suppose you try a different tack, / And on the square you flash your flag?

14. (Internet slang, ACG) An indication that a certain outcome or event is going to happen, deduced not logically or causally, but as a pattern in a piece of media. Chiefly used in video games and adjacent media, especially visual novels, it is typically described as being raised or set by the plot or words of a character.

    set a death flag

    raise the heroine's flags (in a galge)

15. (UK, slang, obsolete) A groat; fourpence.
    • 1851, Henry Mayhew, London Labour and the London Poor, published 1861:

      […] the orator pulled out a tremendous black doll, bought for a ‘flag’ (fourpence) of a retired rag-merchant, and dressed up in Oriental style.

同意語

• (computer science: true-or-false value): Boolean
• (computer science: CLI notation): switch, option
• (geometry: sequence of faces of a polytope): dart

Holonyms

• (piece of cloth): bunting

派生語

動詞

flag (third-person singular simple present flags, present participle flagging, simple past and past participle flagged)

1. To furnish or deck out with flags.
2. To mark with a flag, especially to indicate the importance of something.
   • 2011 January 8, Chris Bevan, “Arsenal 1 - 1 Leeds”, in BBC‎:

     Walcott was, briefly, awarded a penalty when he was upended in the box but referee Phil Dowd reversed his decision because Bendtner had been flagged offside.

3. (often with down) To signal to, especially to stop a passing vehicle etc.

   Please flag down a taxi for me.

   • 1957 December, H. R. Stones, “The Hellingly Hospital Railway”, in Railway Magazine, page 872:

     The electric locomotive is accompanied by a shunter who, in addition to his normal duties, flags the trains over the unprotected level crossings and opens the gates through which the line passes.

4. To convey (a message) by means of flag signals.

   to flag an order to troops or vessels at a distance

5. (often with up) To note, mark or point out for attention.

   I've flagged up the need for further investigation into this.

   Users of the Internet forum can flag others' posts as inappropriate.

6. (computing) To signal (an event).

   The compiler flagged three errors.

7. (computing) To set a program variable to true.

   Flag the debug option before running the program.

8. To decoy (game) by waving a flag, handkerchief, etc. to arouse the animal's curiosity.
   • 1885, Theodore Roosevelt, Hunting Trips of a Ranchman:

     This method of hunting, however, is not so much practised now as formerly, as the antelope are getting continually shyer and more difficult to flag.

9. (sports) To penalize for an infraction.

   The defender was flagged for unsportsmanlike conduct.

10. (chess, intransitive) To lose on time, especially in a blitz game; when using a traditional analog chess clock, a flag would fall when time expired.
    • Mark Dvoretsky (2014), For Friends & Colleagues, volume 1, →ISBN: “Indeed, I usually spent an hour to an hour and a half on my game, never found myself in time pressure, never once flagged in my entire life, except in blitz games, of course.”
11. (chess, transitive) To defeat (an opponent) on time, especially in a blitz game.

    White was winning positionally, but Black managed to flag him and win.

12. (firearms) To point the muzzle of a firearm at a person or object one does not intend to fire on.
13. To fail, such as a class or an exam.

    After he flagged Algebra, Mike was ineligible for the football team.

14. (biology) In female canids, to signal mating readiness by moving the tail aside to expose the vulva.
    • 1996, The Complete Book of Dog Breeding, page 9:

      During estrus, most bitches will flirt with males by backing up to them, flagging their tails in the males’ faces, urinating frequently, and generally acting seductive.

    • 2011 January 3, Pete Haswell, “Life and Behaviour of Wolves”, in Wolf Print‎:

      She will avert her tail to the side (flagging), standing still when the male mounts.

派生語

参考

語源 2

Perhaps from a variant of flack (“to hang loose”), from 中期英語 flacken; or perhaps from Old Norse. Compare Middle Dutch flaggheren, vlaggheren (“to droop, flag”).

動詞

flag (third-person singular simple present flags, present participle flagging, simple past and past participle flagged)

1. (intransitive) To weaken, become feeble.

   His strength flagged toward the end of the race.

   • 1724, Jonathan Swift, “Drapier's Letters”, in 2:

     He now sees a spirit has been raised against him, and he only watches till it begin to flag.

   • 1950 January, David L. Smith, “A Runaway at Beattock”, in Railway Magazine, page 54:

     About half way to Wamphray, they met Mitchell's engine. Her speed was flagging badly. Steam was low, and the fire nearly out.

   • 2012 December 29, Paul Doyle, “Arsenal's Theo Walcott hits hat-trick in thrilling victory over Newcastle”, in The Guardian‎:

     The sides took it in turns to err and excite before Newcastle flagged and Arsenal signalled their top-four credentials by blowing the visitors away.

2. To hang loose without stiffness; to bend down, as flexible bodies; to be loose, yielding, limp.
   • 1817, Thomas Moore, Lalla Rookh […] ‎, London: Longman […] :

     as loose it [the sail] flagged around the mast

3. To let droop; to suffer to fall, or let fall, into feebleness.
   • 1709, Mat[thew] Prior, “An Ode”, in Poems on Several Occasions, London: […] Jacob Tonson […], →OCLC:

     The Thousand Loves , that arm thy potent Eye , Must drop their Quivers , flag their Wings

4. To enervate; to exhaust the vigour or elasticity of.
   • 1670, John Eachard, The Ground and Occasions of the Contempt of the Clergy:

     there is nothing that flags the Spirits, disorders the Blood, and enfeebles the whole Body of Man, as intense Studies.

語源 3

From 中期英語 flagge, of uncertain origin, perhaps from North Germanic; compare Danish flæg (“yellow iris”). Or, possibly from sense 1, referring to its motion in the wind. Compare also Dutch vlag.

名詞

flag (plural flags)

1. Any of various plants with sword-shaped leaves, especially irises; specifically, Iris pseudacorus.
   • c. 1606–1607 (date written), William Shakespeare, “The Tragedie of Anthonie and Cleopatra”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act I, scene iii]:

     [T]he ebbed man, ne'er loved till ne'er worth love,
     Comes deared by being lacked. This common body,
     Like to a vagabond flag upon the stream,
     Goes to and back, lackeying the varying tide,
     To rot itself with motion.

   • 1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], →OCLC, Job 8:11:

     Can the rush grow up without mire? can the flag grow without water?

   • before 1899, Robert Seymour Bridges, There is a Hill:

     And laden barges float

     By banks of myosote;

     And scented flag and golden flower-de-lys

     Delay the loitering boat.

派生語

• sweet flag
• yellow flag

語源 4

From 中期英語 flag, flagge, probably of Scandinavian/North Germanic origin; compare Icelandic flag.

名詞

flag (plural flags)

1. (obsolete except in dialects) A slice of turf; a sod.
2. A slab of stone; a flagstone, a flat piece of stone used for paving.
   • 1980, AA Book of British Villages, Drive Publications Ltd, page 60:

     On market days the farmers would come in before going home - Tysons and Lindsays and Birketts and Longmires and Boows and Dawsons - and their dogs would lie in heaps on the flags while they themselves supped Gerald's ale.

3. (geology) Any hard, evenly stratified sandstone, which splits into layers suitable for flagstones.

動詞

flag (third-person singular simple present flags, present participle flagging, simple past and past participle flagged)

1. (transitive) To pave with flagstones.

   Fred is planning to flag his patio this weekend.

語源 5

名詞

flag (plural flags)

1. A group of feathers on the lower part of the legs of certain hawks, owls, etc.
2. A group of elongated wing feathers in certain hawks.
3. The bushy tail of a dog such as a setter.
4. (music) A hook attached to the stem of a written note that assigns its rhythmic value

参照