The Collaborative International Dictionary of English v.0.48:

Double \Dou"ble\ (d[u^]b"'l), a. [OE. doble, duble, double, OF.
   doble, duble, double, F. double, fr. L. duplus, fr. the root
   of duo two, and perh. that of plenus full; akin to Gr.
   diplo`os double. See Two, and Full, and cf. Diploma,
   Duple.]
   1. Twofold; multiplied by two; increased by its equivalent;
      made twice as large or as much, etc.
      [1913 Webster]

            Let a double portion of thy spirit be upon me. -- 2
                                                  Kings ii. 9.
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            Darkness and tempest make a double night. --Dryden.
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   2. Being in pairs; presenting two of a kind, or two in a set
      together; coupled.
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            [Let] The swan, on still St. Mary's lake,
            Float double, swan and shadow.        --Wordsworth.
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   3. Divided into two; acting two parts, one openly and the
      other secretly; equivocal; deceitful; insincere.
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            With a double heart do they speak.    -- Ps. xii. 2.
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   4. (Bot.) Having the petals in a flower considerably
      increased beyond the natural number, usually as the result
      of cultivation and the expense of the stamens, or stamens
      and pistils. The white water lily and some other plants
      have their blossoms naturally double.
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   Note: Double is often used as the first part of a compound
         word, generally denoting two ways, or twice the number,
         quantity, force, etc., twofold, or having two.
         [1913 Webster]

   Double base, or Double bass (Mus.), the largest and
      lowest-toned instrument in the violin form; the
      contrabasso or violone.

   Double convex. See under Convex.

   Double counterpoint (Mus.), that species of counterpoint or
      composition, in which two of the parts may be inverted, by
      setting one of them an octave higher or lower.

   Double court (Lawn Tennis), a court laid out for four
      players, two on each side.

   Double dagger (Print.), a reference mark ([dag]) next to
      the dagger ([dagger]) in order; a diesis.

   Double drum (Mus.), a large drum that is beaten at both
      ends.

   Double eagle, a gold coin of the United States having the
      value of 20 dollars.

   Double entry. See under Bookkeeping.

   Double floor (Arch.), a floor in which binding joists
      support flooring joists above and ceiling joists below.
      See Illust. of Double-framed floor.

   Double flower. See Double, a., 4.

   Double-framed floor (Arch.), a double floor having girders
      into which the binding joists are framed.

   Double fugue (Mus.), a fugue on two subjects.

   Double letter.
      (a) (Print.) Two letters on one shank; a ligature.
      (b) A mail requiring double postage.

   Double note (Mus.), a note of double the length of the
      semibreve; a breve. See Breve.

   Double octave (Mus.), an interval composed of two octaves,
      or fifteen notes, in diatonic progression; a fifteenth.

   Double pica. See under Pica.

   Double play (Baseball), a play by which two players are put
      out at the same time.

   Double plea (Law), a plea alleging several matters in
      answer to the declaration, where either of such matters
      alone would be a sufficient bar to the action. --Stephen.

   Double point (Geom.), a point of a curve at which two
      branches cross each other. Conjugate or isolated points of
      a curve are called double points, since they possess most
      of the properties of double points (see Conjugate). They
      are also called acnodes, and those points where the
      branches of the curve really cross are called crunodes.
      The extremity of a cusp is also a double point.

   Double quarrel. (Eccl. Law) See Duplex querela, under
      Duplex.

   Double refraction. (Opt.) See Refraction.

   Double salt. (Chem.)
      (a) A mixed salt of any polybasic acid which has been
          saturated by different bases or basic radicals, as the
          double carbonate of sodium and potassium,
          NaKCO3.6H2O.
      (b) A molecular combination of two distinct salts, as
          common alum, which consists of the sulphate of
          aluminium, and the sulphate of potassium or ammonium.


   Double shuffle, a low, noisy dance.

   Double standard (Polit. Econ.), a double standard of
      monetary values; i. e., a gold standard and a silver
      standard, both of which are made legal tender.

   Double star (Astron.), two stars so near to each other as
      to be seen separate only by means of a telescope. Such
      stars may be only optically near to each other, or may be
      physically connected so that they revolve round their
      common center of gravity, and in the latter case are
      called also binary stars.

   Double time (Mil.). Same as Double-quick.

   Double window, a window having two sets of glazed sashes
      with an air space between them.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Double \Dou"ble\, n.
   1. Twice as much; twice the number, sum, quantity, length,
      value, and the like.
      [1913 Webster]

            If the thief be found, let him pay double. --Ex.
                                                  xxii. 7.
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   2. Among compositors, a doublet (see Doublet, 2.); among
      pressmen, a sheet that is twice pulled, and blurred.
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   3. That which is doubled over or together; a doubling; a
      plait; a fold.
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            Rolled up in sevenfold double
            Of plagues.                           --Marston.
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   4. A turn or circuit in running to escape pursues; hence, a
      trick; a shift; an artifice.
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            These men are too well acquainted with the chase to
            be flung off by any false steps or doubles.
                                                  --Addison.
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   5. A person or thing that is the counterpart of another; a
      duplicate; copy; (Obs.) transcript; -- now chiefly used of
      persons. Hence, a wraith.
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            My charming friend . . . has, I am almost sure, a
            double, who preaches his afternoon sermons for him.
                                                  --Atlantic
                                                  Monthly.
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   6. A player or singer who prepares to take the part of
      another player in his absence; a substitute; -- used
      especially of a person who resembles an actor and takes
      the actor's place in scenes requiring special skills; as,
      a stunt double.
      [1913 Webster +PJC]

   7. Double beer; strong beer.
      [1913 Webster]

   8. (Eccl.) A feast in which the antiphon is doubled, hat is,
      said twice, before and after the Psalms, instead of only
      half being said, as in simple feasts. --Shipley.
      [1913 Webster]

   9. (Lawn Tennis) A game between two pairs of players; as, a
      first prize for doubles.
      [1913 Webster]

   10. (Mus.) An old term for a variation, as in Bach's Suites.
       [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Double \Dou"ble\, adv.
   Twice; doubly.
   [1913 Webster]

         I was double their age.                  --Swift.
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The Collaborative International Dictionary of English v.0.48:

Double \Dou"ble\, v. i.
   1. To be increased to twice the sum, number, quantity,
      length, or value; to increase or grow to twice as much.
      [1913 Webster]

            'T is observed in particular nations, that within
            the space of three hundred years, notwithstanding
            all casualties, the number of men doubles. --T.
                                                  Burnet.
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   2. To return upon one's track; to turn and go back over the
      same ground, or in an opposite direction.
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            Doubling and turning like a hunted hare. --Dryden.
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            Doubling and doubling with laborious walk.
                                                  --Wordsworth.
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   3. To play tricks; to use sleights; to play false.
      [1913 Webster]

            What penalty and danger you accrue,
            If you be found to double.            --J. Webster.
      [1913 Webster]

   4. (Print.) To set up a word or words a second time by
      mistake; to make a doublet.
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   To double upon (Mil.), to inclose between two fires.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Double \Dou"ble\, v. t. [imp. & p. p. Doubled; p. pr. & vb. n.
   Doubling.] [OE. doblen, dublen, doublen, F. doubler, fr. L.
   duplare, fr. duplus. See Double, a.]
   1. To increase by adding an equal number, quantity, length,
      value, or the like; multiply by two; as, to double a sum
      of money; to double a number, or length.
      [1913 Webster]

            Double six thousand, and then treble that. --Shak.
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   2. To make of two thicknesses or folds by turning or bending
      together in the middle; to fold one part upon another part
      of; as, to double the leaf of a book, and the like; to
      clinch, as the fist; -- often followed by up; as, to
      double up a sheet of paper or cloth. --Prior.
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            Then the old man
            Was wroth, and doubled up his hands.  --Tennyson.
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   3. To be the double of; to exceed by twofold; to contain or
      be worth twice as much as.
      [1913 Webster]

            Thus re["e]nforced, against the adverse fleet,
            Still doubling ours, brave Rupert leads the way.
                                                  --Dryden.
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   4. To pass around or by; to march or sail round, so as to
      reverse the direction of motion.
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            Sailing along the coast, the doubled the promontory
            of Carthage.                          --Knolles.
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   5. (Mil.) To unite, as ranks or files, so as to form one from
      each two.
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WordNet (r) 3.0 (2006):

double
    adv 1: downward and forward; "he was bent double with pain"
    2: two together; "some people sleep better double"
    3: to double the degree; "she was doubly rewarded"; "his eyes
       were double bright" [syn: doubly, double, twice]
    adj 1: having more than one decidedly dissimilar aspects or
           qualities; "a double (or dual) role for an actor"; "the
           office of a clergyman is twofold; public preaching and
           private influence"- R.W.Emerson; "every episode has its
           double and treble meaning"-Frederick Harrison [syn:
           double, dual, twofold, two-fold, treble,
           threefold, three-fold]
    2: consisting of or involving two parts or components usually in
       pairs; "an egg with a double yolk"; "a double (binary) star";
       "double doors"; "dual controls for pilot and copilot"; "duple
       (or double) time consists of two (or a multiple of two) beats
       to a measure" [syn: double, dual, duple]
    3: twice as great or many; "ate a double portion"; "the dose is
       doubled"; "a twofold increase" [syn: double, doubled,
       twofold, two-fold]
    4: used of flowers having more than the usual number of petals
       in crowded or overlapping arrangements; "double
       chrysanthemums have many rows of petals and are usually
       spherical or hemispherical" [ant: single]
    5: used of homologous chromosomes associated in pairs in
       synapsis [syn: bivalent, double] [ant: multivalent,
       univalent]
    6: large enough for two; "a double bed"; "a double room"
    7: having two meanings with intent to deceive; "a sly double
       meaning"; "spoke with forked tongue" [syn: double,
       forked]
    n 1: a base hit on which the batter stops safely at second base;
         "he hit a double to deep centerfield" [syn: double, two-
         base hit, two-bagger, two-baser]
    2: a stand-in for movie stars to perform dangerous stunts; "his
       first job in Hollywood was as a double for Clark Gable" [syn:
       double, stunt man, stunt woman]
    3: someone who closely resembles a famous person (especially an
       actor); "he could be Gingrich's double"; "she's the very
       image of her mother" [syn: double, image, look-alike]
    4: a quantity that is twice as great as another; "36 is the
       double of 18"
    5: raising the stakes in a card game by a factor of 2; "I
       decided his double was a bluff" [syn: doubling, double]
    v 1: increase twofold; "The population doubled within 50 years"
         [syn: double, duplicate]
    2: hit a two-base hit
    3: bend over or curl up, usually with laughter or pain; "He
       doubled and vomited violently" [syn: double over, double,
       double up]
    4: do double duty; serve two purposes or have two functions;
       "She doubles as his wife and secretary"
    5: bridge: make a demand for (a card or suit)
    6: make or do or perform again; "He could never replicate his
       brilliant performance of the magic trick" [syn: duplicate,
       reduplicate, double, repeat, replicate]

Moby Thesaurus II by Grady Ward, 1.0:

420 Moby Thesaurus words for "double":
   Doppelganger, Janus-like, Machiavellian, Photostat, Xerox,
   aberrancy, aberration, accelerate, act for, actual thing, agent,
   aggravate, alternate, alternative, ambidextrous, ambiguous,
   amplify, analogy, artful, at full speed, at once, augment, average,
   avoid, backup, beef up, beg, bend, bias, bifacial, bifold, biform,
   bifurcated, bilateral, bilk, binary, binate, biparous, bipartisan,
   bipartite, bisect, bivalent, blow up, branching off, briskly,
   carbon copy, change, change places with, changeling,
   circuitousness, circumvent, clone, co-walker, come again,
   come back, come home, companion, comparison, complicate,
   concentrate, condense, conduplicate, consolidate, coordinate, copy,
   corner, counterfeit, counterpart, coupled, crafty, crease,
   creasing, crimp, crisp, crook, crooked, crowd out, cunning, curve,
   cut out, dead ringer, deceitful, declination, deepen, deflection,
   departure, deputy, detour, deviance, deviancy, deviation,
   deviousness, dichotomous, digression, discursion, dishonest,
   disomatous, displace, ditch, ditto, divagation, divarication,
   divergence, diversion, do a repeat, do again, do over, dog-ear,
   dogleg, double back, double for, double over, double-dealing,
   double-faced, double-minded, double-tongued, doubled, doubleganger,
   doublehearted, doubling, drift, drifting, duadic, dual, dualistic,
   dub, duck, dummy, dupe, duple, duplex, duplicate, duplicated,
   duplication, duplicature, duplicitous, dyadic, echo, effigy, elude,
   enfold, enhance, enlarge, equal, equivalent, errantry, ersatz,
   escape, eschew, etheric double, evade, exacerbate,
   exact counterpart, exact likeness, exaggerate, exchange, excursion,
   excursus, exorbitation, facsimile, faithless, fake, false,
   false-principled, falsehearted, fellow, fetch, fill in for,
   fill-in, flection, flexure, flounce, flute, fold, fold over, frill,
   gather, geminate, geminated, get around, get away from, get out of,
   ghost, ghostwrite, ghostwriter, go back, go home, hairpin, heat up,
   hectograph, heighten, homograph, homonym, homophone, hop up,
   hot up, hypocritical, icon, idem, identical, identical same, idol,
   image, imitate, imitation, immediately, increase, indirection,
   infold, ingeminate, insincere, intensify, interfold, jazz up,
   key up, lap over, lapel, lappet, likeness, living image,
   living picture, locum tenens, magnify, make complex, makeshift,
   manifold, match, matched, mate, metaphor, metonymy, microcopy,
   microfilm, middle, mimeo, mimeograph, miniature, mirror image,
   mirroring, model, multigraph, multiply by two, next best thing,
   no other, none other, obliquity, on the run, paired, parrot,
   pererration, perfidious, personnel, phony, photograph, picture,
   pinch hitter, pinch-hit, plagiarize, plait, plat, pleat, plica,
   plicate, plication, plicature, ply, portrait, proxy, put back,
   quadruplicate, quickly, quill, quote, rambling, ramify, reciprocal,
   redo, redouble, reduplicate, reecho, reflection, regurgitate,
   reincarnate, reinforce, relief, relieve, renew, repeat, repetition,
   replace, replacement, replica, replicate, replication, represent,
   representation, representative, reproduce, reproduction,
   resemblance, reserves, return, revive, ringer, rubbing, ruche,
   ruching, ruff, ruffle, say again, second, second string, secondary,
   selfsame, semblance, shadow, shake, shake off, sharpen, sheer,
   shift, shifting, shifting course, shifting path, shifty,
   shuffle out of, shun, shy, sign, similitude, simulacrum, skew,
   skirt, slant, slippery, soup up, spares, spell, spell off, spit,
   spit and image, spitting image, stand in for, stand-in, stat,
   step up, straying, strengthen, sub, subrogate, substituent,
   substitute, substitute for, substitution, succedaneum, succeed,
   supersede, superseder, supplant, supplanter, supplement, surrogate,
   swap places with, sweep, swerve, swerving, swinging, symbol,
   synecdoche, synonym, tack, the same, the same difference,
   third string, token, trace, tracing, traitorous, transcribe,
   treacherous, tricky, triple, triplicate, tuck, turn, turn back,
   turn over, turning, twain, twice, twill, twin, twinned, twist, two,
   two-faced, two-level, two-ply, two-sided, two-story, twofold,
   understudy, understudy for, utility player, variation, veer,
   veering, very image, very picture, very same, vicar,
   vice-president, vice-regent, wandering, warp, whet, without delay,
   wraith, yaw, zigzag



Bouvier's Law Dictionary, Revised 6th Ed (1856):

DOUBLE. Twofold; as, double cost; double insurance; double plea.