The Collaborative International Dictionary of English v.0.48:

Brace \Brace\, n. [OF. brace, brasse, the two arms, embrace,
   fathom, F. brasse fathom, fr. L. bracchia the arms (stretched
   out), pl. of bracchium arm; cf. Gr. ?.]
   1. That which holds anything tightly or supports it firmly; a
      bandage or a prop.
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   2. A cord, ligament, or rod, for producing or maintaining
      tension, as a cord on the side of a drum.
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            The little bones of the ear drum do in straining and
            relaxing it as the braces of the war drum do in
            that.                                 --Derham.
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   3. The state of being braced or tight; tension.
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            The laxness of the tympanum, when it has lost its
            brace or tension.                     --Holder.
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   4. (Arch. & Engin.) A piece of material used to transmit, or
      change the direction of, weight or pressure; any one of
      the pieces, in a frame or truss, which divide the
      structure into triangular parts. It may act as a tie, or
      as a strut, and serves to prevent distortion of the
      structure, and transverse strains in its members. A boiler
      brace is a diagonal stay, connecting the head with the
      shell.
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   5. (Print.) A vertical curved line connecting two or more
      words or lines, which are to be taken together; thus,
      boll, bowl; or, in music, used to connect staves.
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   6. (Naut.) A rope reeved through a block at the end of a
      yard, by which the yard is moved horizontally; also, a
      rudder gudgeon.
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   7. (Mech.) A curved instrument or handle of iron or wood, for
      holding and turning bits, etc.; a bitstock.
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   8. A pair; a couple; as, a brace of ducks; now rarely applied
      to persons, except familiarly or with some contempt. "A
      brace of greyhounds." --Shak.
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            He is said to have shot . . . fifty brace of
            pheasants.                            --Addison.
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            A brace of brethren, both bishops, both eminent for
            learning and religion, now appeared in the church.
                                                  --Fuller.
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            But you, my brace of lords.           --Shak.
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   9. pl. Straps or bands to sustain trousers; suspenders.
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            I embroidered for you a beautiful pair of braces.
                                                  --Thackeray.
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   10. Harness; warlike preparation. [Obs.]
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             For that it stands not in such warlike brace.
                                                  --Shak.
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   11. Armor for the arm; vantbrace.
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   12. (Mining) The mouth of a shaft. [Cornwall]
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   Angle brace. See under Angle.
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The Collaborative International Dictionary of English v.0.48:

Brace \Brace\, v. t. [imp. & p. p. Braced; p. pr. & vb. n.
   Bracing.]
   1. To furnish with braces; to support; to prop; as, to brace
      a beam in a building.
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   2. To draw tight; to tighten; to put in a state of tension;
      to strain; to strengthen; as, to brace the nerves.
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            And welcome war to brace her drums.   --Campbell.
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   3. To bind or tie closely; to fasten tightly.
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            The women of China, by bracing and binding them from
            their infancy, have very little feet. --Locke.
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            Some who spurs had first braced on.   --Sir W.
                                                  Scott.
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   4. To place in a position for resisting pressure; to hold
      firmly; as, he braced himself against the crowd.
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            A sturdy lance in his right hand he braced.
                                                  --Fairfax.
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   5. (Naut.) To move around by means of braces; as, to brace
      the yards.
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   To brace about (Naut.), to turn (a yard) round for the
      contrary tack.

   To brace a yard (Naut.), to move it horizontally by means
      of a brace.

   To brace in (Naut.), to turn (a yard) by hauling in the
      weather brace.

   To brace one's self, to call up one's energies. "He braced
      himself for an effort which he was little able to make."
      --J. D. Forbes.

   To brace to (Naut.), to turn (a yard) by checking or easing
      off the lee brace, and hauling in the weather one, to
      assist in tacking.

   To brace up (Naut.), to bring (a yard) nearer the direction
      of the keel by hauling in the lee brace.

   To brace up sharp (Naut.), to turn (a yard) as far forward
      as the rigging will permit.
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The Collaborative International Dictionary of English v.0.48:

Brace \Brace\, v. i.
   To get tone or vigor; to rouse one's energies; -- with up.
   [Colloq.]
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WordNet (r) 3.0 (2006):

brace
    n 1: a support that steadies or strengthens something else; "he
         wore a brace on his knee"
    2: two items of the same kind [syn: couple, pair, twosome,
       twain, brace, span, yoke, couplet, distich,
       duo, duet, dyad, duad]
    3: a set of two similar things considered as a unit [syn:
       pair, brace]
    4: either of two punctuation marks ( or ) used to enclose
       textual material
    5: a rope on a square-rigged ship that is used to swing a yard
       about and secure it
    6: elastic straps that hold trousers up (usually used in the
       plural) [syn: brace, suspender, gallus]
    7: an appliance that corrects dental irregularities [syn:
       brace, braces, orthodontic braces]
    8: a carpenter's tool having a crank handle for turning and a
       socket to hold a bit for boring [syn: brace, bitstock]
    9: a structural member used to stiffen a framework [syn:
       brace, bracing]
    v 1: prepare (oneself) for something unpleasant or difficult
         [syn: brace, poise]
    2: support or hold steady and make steadfast, with or as if with
       a brace; "brace your elbows while working on the potter's
       wheel" [syn: brace, steady, stabilize, stabilise]
    3: support by bracing
    4: cause to be alert and energetic; "Coffee and tea stimulate
       me"; "This herbal infusion doesn't stimulate" [syn:
       stimulate, arouse, brace, energize, energise, perk
       up] [ant: calm, de-energise, de-energize, sedate,
       tranquilize, tranquillise, tranquillize]

Moby Thesaurus II by Grady Ward, 1.0:

245 Moby Thesaurus words for "brace":
   Ace bandage, Band-Aid, adhesive tape, advocate, afford support,
   alpenstock, animate, appeal, application, arm, athletic supporter,
   back, back up, backbone, backing, band, bandage, bandaging,
   bandeau, bar, bar line, bear, bear up, bearer, beef up, belt, bend,
   beseech, bind, bind up, binder, bolster, bolster up, both, bra,
   brace up, bracer, bracket, brassiere, brisk, brisken, buck up,
   buckle, bundle, buoy up, buttress, cane, carrier, carry,
   case harden, cast, cataplasm, catch, cervix, chain, cheer,
   chirk up, cinch, clamp, clasp, clip, column, compress, confirm,
   corset, cotton, couple, couplet, coupling, court plaster, cradle,
   cravat, crave, crook, crutch, cushion, degree, distich, do up,
   double harness, doublet, dressing, drill, duad, duet, duo, dyad,
   elastic bandage, enliven, entreat, epithem, exhilarate, fastener,
   fortify, foundation garment, four-tailed bandage, fresh up,
   freshen, freshen up, fulcrum, gallows, galluses, gauze, gird,
   girdle, girt, girth, give support, guy, guywire, hang on, harden,
   hold, hold on, hold up, holdfast, implore, importune, invigorate,
   jock, jockstrap, keep afloat, keep up, lace, lash, leash,
   ledger line, lend support, line, lint, mainstay, maintain,
   maintainer, mast, match, mates, neck, nerve, pair, perk up,
   pick up, pillow, plaster, plaster cast, plead, pledget, poultice,
   pray, prop, prop up, quicken, reanimate, recreate, refresh,
   refreshen, regale, reinforce, reinforcement, reinforcer,
   reinvigorate, renew, rest, resting place, restrengthen, revive,
   revivify, rigging, rigidify, roller, roller bandage, rope,
   rubber bandage, screw up, set of two, set up, shore, shore up,
   shoulder, shroud, sling, space, span, spine, splice, splint,
   sponge, sprit, staff, standing rigging, stave, stay, steady, steel,
   stick, stiffen, stiffener, stimulate, strap, strengthen,
   strengthener, strut, stupe, subsidize, subvention, supplicate,
   support, supporter, sustain, sustainer, swaddle, swathe, tampon,
   tape, team, temper, tense, tent, the two, tie, tie up, tighten,
   toughen, tourniquet, triangular bandage, trice up, truss, twain,
   two, twosome, underbrace, undergird, underlie, underpin,
   underpinning, underset, upbear, uphold, upholder, upkeep, vivify,
   walking stick, wire, wrap, wrap up, yoke



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

brace

    left brace or right brace.