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.
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            You must prepare your bosom for his knife. --Shak.
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   2. Specifically: The breasts of a woman; as, an ample bosom.
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   3. The breast, considered as the seat of the passions,
      affections, and operations of the mind; consciousness;
      secret thoughts.
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            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.
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            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.
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            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.
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   2. Intimate; confidential; familiar; trusted; cherished;
      beloved; as, a bosom friend.
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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.
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            Bosom up my counsel,
            You'll find it wholesome.             --Shak.
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   2. To conceal; to hide from view; to embosom.
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            To happy convents bosomed deep in vines. --Pope.
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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]