The Collaborative International Dictionary of English v.0.48:

Breast \Breast\ (br[e^]st), n. [OE. brest, breost, As.
   bre['o]st; akin to Icel. brj[=o]st, Sw. br["o]st, Dan. bryst,
   Goth. brusts, OS. briost, D. borst, G. brust.]
   1. The fore part of the body, between the neck and the belly;
      the chest; as, the breast of a man or of a horse.
      [1913 Webster]

   2. Either one of the protuberant glands, situated on the
      front of the chest or thorax in the female of man and of
      some other mammalia, in which milk is secreted for the
      nourishment of the young; a mamma; a teat.
      [1913 Webster]

            My brother, that sucked the breasts of my mother.
                                                  --Cant. viii.
                                                  1.
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   3. Anything resembling the human breast, or bosom; the front
      or forward part of anything; as, a chimney breast; a plow
      breast; the breast of a hill.
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            Mountains on whose barren breast
            The laboring clouds do often rest.    --Milton.
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   4. (Mining)
      (a) The face of a coal working.
      (b) The front of a furnace.
          [1913 Webster]

   5. The seat of consciousness; the repository of thought and
      self-consciousness, or of secrets; the seat of the
      affections and passions; the heart.
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            He has a loyal breast.                --Shak.
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   6. The power of singing; a musical voice; -- so called,
      probably, from the connection of the voice with the lungs,
      which lie within the breast. [Obs.]
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            By my troth, the fool has an excellent breast.
                                                  --Shak.
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   Breast drill, a portable drilling machine, provided with a
      breastplate, for forcing the drill against the work.

   Breast pang. See Angina pectoris, under Angina.

   To make a clean breast, to disclose the secrets which weigh
      upon one; to make full confession.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Breast \Breast\, v. t. [imp. & p. p. Breasted; p. pr. & vb. n.
   Breasting.]
   To meet, with the breast; to struggle with or oppose
   manfully; as, to breast the storm or waves.
   [1913 Webster]

         The court breasted the popular current by sustaining
         the demurrer.                            --Wirt.
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   To breast up a hedge, to cut the face of it on one side so
      as to lay bare the principal upright stems of the plants.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Brest \Brest\, Breast \Breast\, n. (Arch.)
   A torus. [Obs.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

breast
    n 1: the front of the trunk from the neck to the abdomen; "he
         beat his breast in anger" [syn: breast, chest]
    2: either of two soft fleshy milk-secreting glandular organs on
       the chest of a woman [syn: breast, bosom, knocker,
       boob, tit, titty]
    3: meat carved from the breast of a fowl [syn: breast, white
       meat]
    4: the part of an animal's body that corresponds to a person's
       chest
    v 1: meet at breast level; "The runner breasted the tape"
    2: reach the summit (of a mountain); "They breasted the
       mountain"; "Many mountaineers go up Mt. Everest but not all
       summit" [syn: summit, breast]
    3: confront bodily; "breast the storm" [syn: front, breast]

Moby Thesaurus II by Grady Ward, 1.0:

193 Moby Thesaurus words for "breast":
   Chateaubriand, affront, antagonize, bag, ballocks, balls, basket,
   battle, beard, beat against, beat up against, being, blade roast,
   bones, boob, boobs, bosom, brave, breast the wave, breasts,
   bring before, bring forward, bring up, brisket, buck, buffet,
   buffet the waves, bust, center of life, cervix, challenge, chest,
   chicken foot, chuck, chuck roast, clitoris, clod, close with, cod,
   cods, cold cuts, combat, compete with, confront, confront with,
   contend against, contest, core, crop, cullions, dare, dark meat,
   defy, drumstick, dug, encounter, envisage, esoteric reality,
   esprit, face, face with, family jewels, female organs, fight,
   fight against, filet mignon, flank, front, genitalia, genitals,
   giblets, gonads, grapple with, guts, heart, heart of hearts,
   heartstrings, inmost heart, inmost soul, inner man, inner nature,
   innermost being, inside, join battle with, knocker, knockers,
   knuckle, labia, labia majora, labia minora, labor against,
   lay before, leg, lingam, lips, loin, male organs, mama, mamelon,
   mamelonation, mamma, mammary gland, mammilla, mammillation, meat,
   meet, meet squarely, militate against, neck, nenes, nerve center,
   nipple, nuts, nymphae, offer resistance, ovary, oyster, pap,
   papilla, penis, phallus, pigeon breast, place before, plate,
   plate piece, pot roast, present to, private parts, privates,
   privy parts, pubic hair, pudenda, put it to, quick, rack, reluct,
   reluctate, reproductive organs, rib roast, ribs, rival, roast,
   rocks, rolled roast, round, rump, rump roast, saddle, scrotum,
   secondary sex characteristic, secret heart, secret places,
   set before, sex organs, shank, short ribs, shoulder, shoulder clod,
   sirloin, soul, spermary, spirit, stem, stem the tide,
   strive against, struggle against, take on, teat, tenderloin,
   testes, testicles, thigh, thorax, tit, tits, titties, titty,
   true being, true inwardness, turkey foot, udder, uterus, vagina,
   vie with, viscera, vital principle, vitals, vulva, white meat,
   wing, wishbone, womb, yoni