A hollow area within the body.
A hole or hollow depression in a solid object.
A small or large hole in a tooth caused by caries; often also a soft area adjacent to the hole also affected by caries.
The bore of a tube such as a hollow needle or catheter.
In the International System of Units, the derived unit of luminous flux; the light that is emitted in a solid angle of one steradian from a source of one candela. Symbol: lm.
The cavity bounded by a plant cell wall.
The cavity or channel within a tube or tubular organ.