The Collaborative International Dictionary of English v.0.48:

Belly \Bel"ly\ (b[e^]l"l[y^]), n.; pl. Bellies (-l[i^]z). [OE.
   bali, bely, AS. belg, b[ae]lg, b[ae]lig, bag, bellows, belly;
   akin to Icel. belgr bag, bellows, Sw. b[aum]lg, Dan. b[ae]lg,
   D. & G. balg, cf. W. bol the paunch or belly, dim. boly, Ir.
   bolg. Cf. Bellows, Follicle, Fool, Bilge.]
   1. That part of the human body which extends downward from
      the breast to the thighs, and contains the bowels, or
      intestines; the abdomen.
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   Note: Formerly all the splanchnic or visceral cavities were
         called bellies; -- the lower belly being the abdomen;
         the middle belly, the thorax; and the upper belly, the
         head. --Dunglison.
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   2. The under part of the body of animals, corresponding to
      the human belly.
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            Underneath the belly of their steeds. --Shak.
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   3. The womb. [Obs.]
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            Before I formed thee in the belly I knew thee.
                                                  --Jer. i. 5.
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   4. The part of anything which resembles the human belly in
      protuberance or in cavity; the innermost part; as, the
      belly of a flask, muscle, sail, ship.
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            Out of the belly of hell cried I.     --Jonah ii. 2.
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   5. (Arch.) The hollow part of a curved or bent timber, the
      convex part of which is the back.
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   Belly doublet, a doublet of the 16th century, hanging down
      so as to cover the belly. --Shak.

   Belly fretting, the chafing of a horse's belly with a
      girth. --Johnson.

   Belly timber, food. [Ludicrous] --Prior.

   Belly worm, a worm that breeds or lives in the belly
      (stomach or intestines). --Johnson.
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The Collaborative International Dictionary of English v.0.48:

Belly \Bel"ly\, v. t. [imp. & p. p. Bellied; p. pr. & vb. n.
   Bellying.]
   To cause to swell out; to fill. [R.]
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         Your breath of full consent bellied his sails. --Shak.
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The Collaborative International Dictionary of English v.0.48:

Belly \Bel"ly\, v. i.
   To swell and become protuberant, like the belly; to bulge.
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         The bellying canvas strutted with the gale. --Dryden.
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WordNet (r) 3.0 (2006):

belly
    n 1: the region of the body of a vertebrate between the thorax
         and the pelvis [syn: abdomen, venter, stomach,
         belly]
    2: a protruding abdomen [syn: belly, paunch]
    3: a part that bulges deeply; "the belly of a sail"
    4: the hollow inside of something; "in the belly of the ship"
    5: the underpart of the body of certain vertebrates such as
       snakes or fish
    v 1: swell out or bulge out [syn: belly, belly out]