that part of the human body which extends downward from the breast to the thighs, and contains the bowels, or intestines; the abdomen.-the under part of the body of animals, corresponding to the human belly.-the womb.-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.-the hollow part of a curved or bent timber, the convex part of which is the back.-to cause to swell out; to fill.-to swell and become protuberant, like the belly; to bulge.