Lumen

Pronunciation

Full definition of lumen

Noun

1. (physics) 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.
2. (anatomy) The cavity or channel within a tube or tubular organ.
3. (botany) The cavity bounded by a plant cell wall.
4. (medicine) The bore of a tube such as a hollow needle or catheter.

Derived terms

• lumenal
• luminal