1590s, from Rus. beluga
, lit. "great white," from belo-
"white" (from PIE *bhel-o-
, from base *bhel-
(1) "to shine, flash, burn;" see bleach
) + augmentative suffix -uga
. Originally the great sturgeon, found in the Caspian and Black seas; later (1817) also the small white whale (Delphinapterus leucas
) found in northern seas.