noun pl. beluga -·ga or belugas -·gas

1. a large, white sturgeon (Huso huso) of the Black Sea and the Caspian Sea
2. a large, white toothed whale (Delphinapterus leucas) of northern seas: it is in the same family (Monodontidae) as the narwhal
3. caviar prepared from the eggs of the white sturgeon
   also called beluga caviar

Etymology: < Russ < byelyj, white (Russ byeluga, the sturgeon & byelukha, the whale) < IE base *bhel-, to gleam: see black