a large white sturgeon (Huso huso synonym Acipenser huso) of the Black Sea, Caspian Sea, and their tributaries; also : caviar processed from beluga roe
belugas
noun(be-lu-ga)
a toothed whale (Delphinapterus leucas) of arctic and subarctic waters having a fusiform body that is about 10 to 15 feet (3.0 to 5.0 meters) long and white when mature —called also white whale