lumen
英 ['luːmen]
美['lumɛn]
	    - n. 流明(光束的能量单位);(管状器官内的)内腔
 
英英释意
- 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
 
- 2. a cavity or passage in a tubular organ;
 - "the lumen of the intestine"