Source : Webster's Revised Unabridged Dictionary (1913)

Albedo \Al*be"do\, n. [L., fr. albus white.]
   Whiteness. Specifically: (Astron.) The ratio which the light
   reflected from an unpolished surface bears to the total light
   falling upon that surface.

Source : WordNet®

albedo
     n : the ratio of reflected to incident light [syn: {reflective
         power}]