(1) A cavity or passage in a tubular organ
"The lumen of the intestine"
(2) A unit of luminous flux equal to the amount of light given out through a solid angle of 1 steradian by a point source of 1 candela intensity radiating uniformly in all directions
- In the International System of Units, the derived unit of luminous flux; the amount of light that falls on a unit area at unit distance from a source of one candela. Symbol: lm.
- The cavity or channel within a tube or tubular organ.
- The cavity bounded by a plant cell wall.
- The bore of a tube such as a hollow needle or catheter.