lumen

Meaning

Noun

• 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 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.

Origin

• Borrowed from Latin lumen ("light, an opening"). Use as a unit was first adopted by French physicist André Blondel in 1894.