1 Physics the SI unit of luminous flux, equal to the amount of light emitted per second in a unit solid angle of one steradian from a uniform source of one candela.
Usage:
Abbr.: lm.
2 Anat. (pl. lumina) a cavity within a tube, cell, etc.
Derivatives:
luminal adj.
Etymology: L lumen luminis a light, an opening
Useful english dictionary. 2012.