cav·i·ty 
(kăvĭ-tē)
(kăvĭ-tē)n. pl. cav·i·ties
1. A hollow; a hole.
2. A hollow area within the body: a sinus cavity.
3. A pitted area in a tooth caused by caries.
[French cavité, from Late Latin cavitās, from Latin cavus, hollow; see keuə- in the Appendix of Indo-European roots.]