basking shark

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A very large shark (Cetorhinus maximus) that measures up to about 12 meters (40 feet) in length, feeds on plankton, and often floats near the surface of water.

Century Dictionary and Cyclopedia

1. n. A popular name of the Cetorhinus maximus (or Selache maxima), one of the largest of the sharks. It is an inhabitant of the northern seas, and has been known to reach the length of 40 feet. It frequently comes to the surface and basks in the sunshine. Its food consists chiefly of small animals, which are strained from the water by a peculiar development of the gill-structures. The liver is very large and yields a great quantity of oil, as much as twelve barrels having been obtained from a single individual. Other popular names are bone-shark (by which it is generally known along the American coast), homer or hoemother, sailfish, and sunfish. See Cetorhinidæ.

Wiktionary

1. n. A very large shark, Cetorhinus maximus, that feeds at or close to the surface by filtering plankton from the water and is found in all the world's temperate oceans.

GNU Webster's 1913

1. (Zoöl.) One of the largest species of sharks (Cetorhinus maximus), so called from its habit of basking in the sun; the liver shark, or bone shark. It inhabits the northern seas of Europe and America, and grows to a length of more than forty feet. It is a harmless species.
2. n. See under Basking, Liver, etc. See also Dogfish, Houndfish, Notidanian, and Tope.

WordNet 3.0

1. n. large harmless plankton-eating northern shark; often swims slowly or floats at the sea surface