lumen
/ˈluːmən/
noun 4
Definitions
noun
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. Symbol: lm.
2
The cavity or channel within a tube or tubular organ.
3
The cavity bounded by a plant cell wall.
4
The bore of a tube such as a hollow needle or catheter.
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