lumen

Từ điển WordNet v3.1 - WordNet Dictionary

noun

1. 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
• Syn:
lm
• Hypernyms:
luminous flux unit
2. a cavity or passage in a tubular organ
- the lumen of the intestine
• Hypernyms:
cavity, bodily cavity, cavum