Source : Webster's Revised Unabridged Dictionary (1913)

Cavity \Cav"i*ty\, n.; pl. {Cavities}. [L. cavus hollow: cf. F.
   cavit['e].]
   1. Hollowness. [Obs.]

            The cavity or hollowness of the place. --Goodwin.

   2. A hollow place; a hollow; as, the abdominal cavity.

            An instrument with a small cavity, like a small
            spoon.                                --Arbuthnot.

            Abnormal spaces or excavations are frequently formed
            in the lungs, which are designated cavities or
            vomic[ae].                            --Quain.

   {Body cavity}, the c[oe]lum. See under {Body}.

Source : WordNet®

cavity
     n 1: a sizeable hole (usually in the ground); "they dug a pit to
          bury the body" [syn: {pit}]
     2: space that is surrounded by something [syn: {enclosed space}]
     3: soft decayed area in a tooth; progressive decay can lead to
        the death of a tooth [syn: {caries}, {dental caries}, {tooth
        decay}]
     4: (anatomy) a natural hollow or sinus within the body [syn: {bodily
        cavity}, {cavum}]