beluga

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. See white whale.
2. n. A large white sturgeon (Huso huso) of the Black and Caspian seas, whose roe is processed into caviar. Also called beluga sturgeon, whitefish.

Century Dictionary and Cyclopedia

1. n. The large white sturgeon, Acipenser huso, from the roe of which, sometimes weighing 800 pounds, caviar or botargo is prepared. The fish is from 12 to 15 feet in length, weighing in some cases 2,000 pounds or more. Isinglass is prepared from its swim-bladder.
2. n. [capitalized] [NL.] A generic name of the white whales: a synonym of Delphinapterus. The only species found in northern seas is B. arctica, leucas, or albicans, which from its color is commonly called white whale or whitefish. It is from 12 to 18 feet in length. The tail is divided into two lobes, lying horizontally, and there is no dorsal fin. In swimming, the animal bends its tail under its body like a lobster, and thrusts itself along with the rapidity of an arrow. It is found in the arctic seas and rivers, and is caught for its oil and its skin.

Wiktionary

1. n. A cetacean, Delphinapterus leucas, found in the Arctic Ocean.
2. n. A fish, Huso huso, found in the Caspian Sea and the Black Sea, that is a source of caviar

GNU Webster's 1913

1. n. A cetacean allied to the dolphins.
2. n. the sturgeon (Huso huso) native to the Black Sea and Caspian Sea; -- also called hausen. It is valued for its roe, sold as caviar, and is also used for production of isinglass. See also sturgeon.
3. n. the caviar obtained from the beluga{2}; -- also called beluga caviar. The caviar of the beluga is considered the finest sort, larger and of a taste superior to that obtained from other sturgeon. See also sturgeon and caviar.

WordNet 3.0

1. n. valuable source of caviar and isinglass; found in Black and Caspian seas
2. n. small northern whale that is white when adult