1590s, from Russian beluga, literally "great white," from belo- "white" (from PIE *bhel-o-, suffixed form of root *bhel- (1) "to shine, flash, burn," also "shining white") + augmentative suffix -uga. Originally the great white sturgeon, found in the Caspian and Black seas; later (1817) the popular name for the small white whale (Delphinapterus leucas) found in northern seas.