/ˈlo͞omən/
Noun, pl. lumens
(Physics)
1. 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. (wiktionary.org)
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
Symbol: lm
Noun, pl. lumina
(Anatomy)
The cavity or channel within a tube or tubular organ. (wiktionary.org)
(Botany)
The cavity bounded by a plant cell wall. (wiktionary.org)
(Medicine)
The bore of a tube such as a hollow needle or catheter. (wiktionary.org)
Word origin: From Latin lumen “light,” related to lucere “to shine”