cavity

noun4

1. •
   A hole or hollow depression in a solid object.
2. •
   A hollow area within the body.
3. •
   The female part of a mold: the depression itself or (metonymically) the half of the mold that contains it.
4. •
   A small or large hole in a tooth caused by caries; often also a soft area adjacent to the hole also affected by caries.

   • Jim got two cavities filled at the dentist's office yesterday.