The Collaborative International Dictionary of English v.0.48:

Flag \Flag\ (fl[a^]g), v. i. [imp. & p. p. Flagged (fl[a^]gd);
   p. pr. & vb. n. Flagging (fl[a^]g"g[i^]ng).] [Cf. Icel.
   flaka to droop, hang loosely. Cf. Flacker, Flag an
   ensign.]
   1. To hang loose without stiffness; to bend down, as flexible
      bodies; to be loose, yielding, limp.
      [1913 Webster]

            As loose it [the sail] flagged around the mast. --T.
                                                  Moore.
      [1913 Webster]

   2. To droop; to grow spiritless; to lose vigor; to languish;
      as, the spirits flag; the strength flags.
      [1913 Webster]

            The pleasures of the town begin to flag. --Swift.

   Syn: To droop; decline; fail; languish; pine.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Flag \Flag\, v. t. [From Flag an ensign.]
   1. To signal to with a flag or by waving the hand; as, to
      flag a train; also used with down; as, to flag down a cab.
      [1913 Webster]

   2. To convey, as a message, by means of flag signals; as, to
      flag an order to troops or vessels at a distance.
      [1913 Webster]

   3. To decoy (game) by waving a flag, handkerchief, or the
      like to arouse the animal's curiosity.

            The antelope are getting continually shyer and more
            difficult to flag.                    --T.
                                                  Roosevelt.
      [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Flag \Flag\, n. [From Flag to hang loose, to bend down.]
   (Bot.)
   An aquatic plant, with long, ensiform leaves, belonging to
   either of the genera Iris and Acorus.
   [1913 Webster]

   Cooper's flag, the cat-tail (Typha latifolia), the long
      leaves of which are placed between the staves of barrels
      to make the latter water-tight.

   Corn flag. See under 2d Corn.

   Flag broom, a coarse of broom, originally made of flags or
      rushes.

   Flag root, the root of the sweet flag.

   Sweet flag. See Calamus, n., 2.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Flag \Flag\ (fl[a^]g), v. t.
   1. To let droop; to suffer to fall, or let fall, into
      feebleness; as, to flag the wings. --prior.
      [1913 Webster]

   2. To enervate; to exhaust the vigor or elasticity of.
      [1913 Webster]

            Nothing so flags the spirits.         --Echard.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Flag \Flag\, n. [Cf. LG. & G. flagge, Sw. flagg, Dan. flag, D.
   vlag. See Flag to hang loose.]
   1. That which flags or hangs down loosely.
      [1913 Webster]

   2. A cloth usually bearing a device or devices and used to
      indicate nationality, party, etc., or to give or ask
      information; -- commonly attached to a staff to be waved
      by the wind; a standard; a banner; an ensign; the colors;
      as, the national flag; a military or a naval flag.
      [1913 Webster]

   3. (Zool.)
      (a) A group of feathers on the lower part of the legs of
          certain hawks, owls, etc.
      (b) A group of elongated wing feathers in certain hawks.
      (c) The bushy tail of a dog, as of a setter.
          [1913 Webster]

   4. (Zool.) One of the wing feathers next the body of a bird;
      -- called also flag feather.
      [Webster 1913 Suppl.]

   Black flag. See under Black.

   Flag captain, Flag leutenant, etc., special officers
      attached to the flagship, as aids to the flag officer.

   Flag officer, the commander of a fleet or squadron; an
      admiral, or commodore.

   Flag of truse, a white flag carried or displayed to an
      enemy, as an invitation to conference, or for the purpose
      of making some communication not hostile.

   Flag share, the flag officer's share of prize money.

   Flag station (Railroad), a station at which trains do not
      stop unless signaled to do so, by a flag hung out or
      waved.

   National flag, a flag of a particular country, on which
      some national emblem or device, is emblazoned.

   Red flag, a flag of a red color, displayed as a signal of
      danger or token of defiance; the emblem of anarchists.

   To dip, the flag, to mlower it and quickly restore it to
      its place; -- done as a mark of respect.

   To hang out the white flag, to ask truce or quarter, or, in
      some cases, to manifest a friendly design by exhibiting a
      white flag.

   To hang the flag half-mast high or To hang the flag
   half-staff or To hang the flag at half-staff, to raise it
      only half way to the mast or staff, as a token or sign of
      mourning.

   To strike the flag or To lower the flag, to haul it down,
      in token of respect, submission, or, in an engagement, of
      surrender.

   Yellow flag, the quarantine flag of all nations; also
      carried at a vessel's fore, to denote that an infectious
      disease is on board.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Flag \Flag\, v. t.
   To furnish or deck out with flags.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Flag \Flag\, n. [Icel. flaga, cf. Icel. flag spot where a turf
   has been cut out, and E. flake layer, scale. Cf. Floe.]
   1. A flat stone used for paving. --Woodward.
      [1913 Webster]

   2. (Geol.) Any hard, evenly stratified sandstone, which
      splits into layers suitable for flagstones.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Flag \Flag\, v. t.
   To lay with flags of flat stones.
   [1913 Webster]

         The sides and floor are all flagged with . . . marble.
                                                  --Sandys.
   [1913 Webster]

WordNet (r) 3.0 (2006):

flag
    n 1: emblem usually consisting of a rectangular piece of cloth
         of distinctive design
    2: a listing printed in all issues of a newspaper or magazine
       (usually on the editorial page) that gives the name of the
       publication and the names of the editorial staff, etc. [syn:
       masthead, flag]
    3: plants with sword-shaped leaves and erect stalks bearing
       bright-colored flowers composed of three petals and three
       drooping sepals [syn: iris, flag, fleur-de-lis, sword
       lily]
    4: a rectangular piece of fabric used as a signalling device
       [syn: flag, signal flag]
    5: flagpole used to mark the position of the hole on a golf
       green [syn: pin, flag]
    6: stratified stone that splits into pieces suitable as paving
       stones [syn: flag, flagstone]
    7: a conspicuously marked or shaped tail
    v 1: communicate or signal with a flag
    2: provide with a flag; "Flag this file so that I can recognize
       it immediately"
    3: droop, sink, or settle from or as if from pressure or loss of
       tautness [syn: sag, droop, swag, flag]
    4: decorate with flags; "the building was flagged for the
       holiday"
    5: become less intense [syn: ease up, ease off, slacken
       off, flag]

Moby Thesaurus II by Grady Ward, 1.0:

318 Moby Thesaurus words for "flag":
   Dannebrog, Jolly Roger, Old Glory, Star-Spangled Banner,
   Stars and Stripes, Tarmac, Tarvia, Union Flag, Union Jack, abate,
   adobe, and blue, ashlar, asphalt, banderole, banner, banneret,
   bead, beat, beat the drum, bejewel, beribbon, bespangle, bitumen,
   bituminous macadam, black flag, blacktop, blade, blow, blue ensign,
   bract, bracteole, bractlet, break, break down, brick,
   bricks and mortar, bunting, burgee, burn out, carpet, causeway,
   cave in, cement, check off, clinker, coachwhip, cobble,
   cobblestone, collapse, color, colors, come apart, come unstuck,
   concrete, conk out, cotyledon, covering materials, crack up,
   crumble, curb, curbing, curbstone, dally, dangle, dawdle,
   debilitate, decline, decrease, degenerate, delay, desiccate,
   deteriorate, diamond, die, dillydally, diminish, dip, disintegrate,
   do in, do up, drag, droop, drop, dry up, dwindle, ease up, ebb,
   edgestone, enervate, engrave, ensign, exchange colors, exhaust,
   fade, fade away, fag, fag out, fail, faint, fall off, falter,
   fatigue, feather, ferroconcrete, festoon, figure, filigree,
   firebrick, fizzle out, flag down, flagging, flagstone, flash,
   floor, flooring, floral leaf, flounce, flower, foliole, frazzle,
   frond, garland, gasp, gem, gesture, get tired, give a signal,
   give out, give the nod, give way, glance, glume, go downhill,
   go soft, go to pieces, gonfalon, gonfanon, goof off, gravel,
   grow weary, guidon, hail, hail and speak, half-mast, halt,
   hang down, harass, hit the skids, hoist a banner, house flag,
   identify, illuminate, inform, involucre, involucrum, jack, jade,
   jewel, kerb, kerbstone, kick, knock out, knock up, label, lag,
   lamina, languish, lath and plaster, leaf, leaflet, leer, lemma,
   lessen, let up, ligule, linger, loiter, lollygag, long pennant,
   lose strength, macadam, make a sign, mark, masonry, merchant flag,
   metal, mortar, motion, national flag, needle, nod, nudge,
   oriflamme, overfatigue, overstrain, overtire, overweary, paint,
   pant, pave, pavement, pavestone, paving, paving material,
   paving stone, peak, pebble, peg out, pendant, pennant, pennon,
   pennoncel, petal, peter out, pile, pine, pine needle, plasters,
   play out, plume, poke, poop, poop out, prestressed concrete,
   prostrate, puff, puff and blow, raise a cry, red, red ensign,
   ribbon, road metal, roofage, roofing, royal standard, run down,
   run out, sag, salute, sear, seed leaf, sepal, shilly-shally,
   shrink, shrivel, siding, sign, signal, signal flag, signalize,
   sink, slump, sound an alarm, sound the trumpet, spangle, spathe,
   speak, spear, spire, standard, stipula, stipule, stone, stop,
   streamer, subside, succumb, swag, swallowtail, tab, tag, taper off,
   tar, tarmacadam, tarry, tick off, tile, tiling, tinsel, tire,
   tire out, tire to death, touch, trail, tricolor, tucker,
   unfurl a flag, use up, vexillum, walling, wane, warn, washboard,
   waste, waste away, waste time, wave, wave a flag, wave the hand,
   weaken, wear, wear away, wear down, wear on, wear out, wear thin,
   weary, wheeze, white, wilt, wind, wink, wither, wither away, wizen,
   wreathe, yield



The Jargon File (version 4.4.7, 29 Dec 2003):

flag
 n.

    [very common] A variable or quantity that can take on one of two values; a
    bit, particularly one that is used to indicate one of two outcomes or is
    used to control which of two things is to be done. ?This flag controls
    whether to clear the screen before printing the message.? ?The program
    status word contains several flag bits.? Used of humans analogously to bit
    . See also hidden flag, mode bit.


The Free On-line Dictionary of Computing (30 December 2018):

flag

   1.  A variable or quantity that can take on one
   of two values; a bit, particularly one that is used to
   indicate one of two outcomes or is used to control which of
   two things is to be done.  "This flag controls whether to
   clear the screen before printing the message."  "The program
   status word contains several flag bits."  See also hidden
   flag, mode bit.

   2. command line option.

   [Jargon File]

   (1998-05-02)


Easton's 1897 Bible Dictionary:

Flag
   (Heb., or rather Egyptian, ahu, Job 8:11), rendered "meadow" in
   Gen. 41:2, 18; probably the Cyperus esculentus, a species of
   rush eaten by cattle, the Nile reed. It also grows in Palestine.

     In Ex. 2:3, 5, Isa. 19:6, it is the rendering of the Hebrew
   _suph_, a word which occurs frequently in connection with _yam_;
   as _yam suph_, to denote the "Red Sea" (q.v.) or the sea of
   weeds (as this word is rendered, Jonah 2:5). It denotes some
   kind of sedge or reed which grows in marshy places. (See PAPER
   ¯T0002840, REED.)


The Devil's Dictionary (1881-1906):

FLAG, n.  A colored rag borne above troops and hoisted on forts and
ships.  It appears to serve the same purpose as certain signs that one
sees and vacant lots in London -- "Rubbish may be shot here."