The Collaborative International Dictionary of English v.0.48:

Boast \Boast\, v. i. [imp. & p. p. Boasted; p. pr. & vb. n.
   Boasting.] [OE. bosten, boosten, v., bost, boost, n.,
   noise, boasting; cf. G. bausen, bauschen, to swell, pusten,
   Dan. puste, Sw. pusta, to blow, Sw. p["o]sa to swell; or W.
   bostio to boast, bost boast, Gael. bosd. But these last may
   be from English.]
   1. To vaunt one's self; to brag; to say or tell things which
      are intended to give others a high opinion of one's self
      or of things belonging to one's self; as, to boast of
      one's exploits courage, descent, wealth.
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            By grace are ye saved through faith; and that not of
            yourselves: . . not of works, lest any man should
            boast.                                --Eph. ii. 8,
                                                  9.
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   2. To speak in exulting language of another; to glory; to
      exult.
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            In God we boast all the day long.     --Ps. xliv. 8
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   Syn: To brag; bluster; vapor; crow; talk big.
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The Collaborative International Dictionary of English v.0.48:

Boast \Boast\, v. t.
   1. To display in ostentatious language; to speak of with
      pride, vanity, or exultation, with a view to
      self-commendation; to extol.
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            Lest bad men should boast
            Their specious deeds.                 --Milton.
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   2. To display vaingloriously.
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   3. To possess or have; as, to boast a name.
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   To boast one's self, to speak with unbecoming confidence
      in, and approval of, one's self; -- followed by of and the
      thing to which the boasting relates. [Archaic]
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            Boast not thyself of to-morrow.       --Prov. xxvii.
                                                  1
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The Collaborative International Dictionary of English v.0.48:

Boast \Boast\, v. t. [Of uncertain etymology.]
   1. (Masonry) To dress, as a stone, with a broad chisel.
      --Weale.
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   2. (Sculp.) To shape roughly as a preparation for the finer
      work to follow; to cut to the general form required.
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The Collaborative International Dictionary of English v.0.48:

Boast \Boast\, n.
   1. Act of boasting; vaunting or bragging.
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            Reason and morals? and where live they most,
            In Christian comfort, or in Stoic boast! --Byron.
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   2. The cause of boasting; occasion of pride or exultation, --
      sometimes of laudable pride or exultation.
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            The boast of historians.              --Macaulay.
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WordNet (r) 3.0 (2006):

boast
    n 1: speaking of yourself in superlatives [syn: boast,
         boasting, self-praise, jactitation]
    v 1: show off [syn: boast, tout, swash, shoot a line,
         brag, gas, blow, bluster, vaunt, gasconade]
    2: wear or display in an ostentatious or proud manner; "she was
       sporting a new hat" [syn: sport, feature, boast]

Moby Thesaurus II by Grady Ward, 1.0:

89 Moby Thesaurus words for "boast":
   aggrandize, be enfeoffed of, be possessed of, be seized of, blow,
   bluster, boastfulness, boasting, bombast, bounce, brag,
   braggadocio, braggartism, bragging, bravado, bully, catch, claim,
   cock-a-doodle-doo, command, conceit, crow, diamond,
   draw the longbow, ego-trip, enjoy, exalt, fanfaronade, fill, find,
   fish for compliments, flaunt, flourish, gasconade, gasconism, gem,
   glory, godsend, good thing, gush, have, have and hold,
   have in hand, have no self-doubt, have tenure of, heroics, hold,
   jactation, jactitation, jewel, know it all, mouth, occupy, parade,
   pearl, pique, plum, plume, possess, prate, preen, pride,
   pride and joy, prize, puff, quack, rodomontade, ruffle, show off,
   side, speak for Buncombe, squat, squat on, swagger, swash,
   swashbuckle, talk big, treasure, triumph, trophy, trouvaille,
   usucapt, vanity, vapor, vaunt, vauntery, vaunting, windfall,
   winner