The Collaborative International Dictionary of English v.0.48:

Bosom \Bos"om\ (b[oo^]z"[u^]m; 277), n. [AS. b[=o]sm; akin to D.
   bozem, Fries. b[=o]sm, OHG. puosum, G. busen, and prob. E.
   bough.]
   1. The breast of a human being; the part, between the arms,
      to which anything is pressed when embraced by them.
      [1913 Webster]

            You must prepare your bosom for his knife. --Shak.
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   2. Specifically: The breasts of a woman; as, an ample bosom.
      [PJC]

   3. The breast, considered as the seat of the passions,
      affections, and operations of the mind; consciousness;
      secret thoughts.
      [1913 Webster]

            Tut, I am in their bosoms, and I know
            Wherefore they do it.                 --Shak.
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            If I covered my transgressions as Adam, by hiding my
            iniquity in my bosom.                 --Job xxxi.
                                                  33.
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   4. Embrace; loving or affectionate inclosure; fold.
      [1913 Webster]

            Within the bosom of that church.      --Hooker.
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   5. Any thing or place resembling the breast; a supporting
      surface; an inner recess; the interior; as, the bosom of
      the earth. "The bosom of the ocean." --Addison.
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   6. The part of the dress worn upon the breast; an article, or
      a portion of an article, of dress to be worn upon the
      breast; as, the bosom of a shirt; a linen bosom.
      [1913 Webster]

            He put his hand into his bosom: and when he took it
            out, behold, his hand was leprous as snow. --Ex. iv.
                                                  6.
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   7. Inclination; desire. [Obs.] --Shak.
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   8. A depression round the eye of a millstone. --Knight.
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The Collaborative International Dictionary of English v.0.48:

bosom \bos"om\, a.
   1. Of or pertaining to the bosom.
      [1913 Webster]

   2. Intimate; confidential; familiar; trusted; cherished;
      beloved; as, a bosom friend.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

bosom \bos"om\, v. t. [imp. & p. p. Bosomed (-[u^]md); p. pr.
   & vb. n. Bosoming.]
   1. To inclose or carry in the bosom; to keep with care; to
      take to heart; to cherish.
      [1913 Webster]

            Bosom up my counsel,
            You'll find it wholesome.             --Shak.
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   2. To conceal; to hide from view; to embosom.
      [1913 Webster]

            To happy convents bosomed deep in vines. --Pope.
      [1913 Webster]

WordNet (r) 3.0 (2006):

bosom
    n 1: the chest considered as the place where secret thoughts are
         kept; "his bosom was bursting with the secret"
    2: a person's breast or chest
    3: cloth that covers the chest or breasts
    4: a close affectionate and protective acceptance; "his willing
       embrace of new ideas"; "in the bosom of the family" [syn:
       embrace, bosom]
    5: the locus of feelings and intuitions; "in your heart you know
       it is true"; "her story would melt your bosom" [syn: heart,
       bosom]
    6: either of two soft fleshy milk-secreting glandular organs on
       the chest of a woman [syn: breast, bosom, knocker,
       boob, tit, titty]
    v 1: hide in one's bosom; "She bosomed his letters"
    2: squeeze (someone) tightly in your arms, usually with
       fondness; "Hug me, please"; "They embraced"; "He hugged her
       close to him" [syn: embrace, hug, bosom, squeeze]

Moby Thesaurus II by Grady Ward, 1.0:

147 Moby Thesaurus words for "bosom":
   bag, bear, being, beloved, blood, bones, boobs, boon, bottle up,
   bowels, breast, breasts, brisket, bury, bust, cache, center,
   center of life, cherish, cherished, chest, clasp, classify,
   cling to, clip, close, conceal, confidential, core, crop, dear,
   deepest recesses, deposit, dug, embosom, embrace, enfold,
   entertain, esoteric reality, esprit, file and forget, fold, fondle,
   foster, gut, guts, harbor, have, have and hold, heart,
   heart of hearts, heartstrings, hide away, hold, hold on to,
   hold out on, hug, in petto, inmost heart, inmost soul, inner,
   inner landscape, inner life, inner man, inner nature, inner recess,
   inner self, innermost being, inside, interior, interior man,
   intern, internal, intimate, intrados, inward, keep, keep back,
   keep between us, keep buttoned up, keep close, keep dark,
   keep from, keep hidden, keep in ignorance, keep mum, keep secret,
   keep snug, keep under wraps, knockers, lock up, make no sign, mama,
   mamelon, mamelonation, mammary gland, mammilla, mammillation,
   midst, nenes, nerve center, never let on, nipple, not give away,
   not tell, nurse, nurture, pair, pap, papilla, penetralia,
   pigeon breast, plant, play dumb, press, put away, quick, recesses,
   seal up, secret heart, secret place, secret places, secrete, soul,
   special, spirit, squeeze, stash, store away, stow away, teat,
   thorax, tit, tits, titties, titty, treasure, treasure up,
   true being, true inwardness, udder, veil, viscera, vital center,
   vital principle, vitals, withhold



Easton's 1897 Bible Dictionary:

Bosom
   In the East objects are carried in the bosom which Europeans
   carry in the pocket. To have in one's bosom indicates kindness,
   secrecy, or intimacy (Gen. 16:5; 2 Sam. 12:8). Christ is said to
   have been in "the bosom of the Father," i.e., he had the most
   perfect knowledge of the Father, had the closest intimacy with
   him (John 1:18). John (13:23) was "leaning on Jesus' bosom" at
   the last supper. Our Lord carries his lambs in his bosom, i.e.,
   has a tender, watchful care over them (Isa. 40:11).