basking shark

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun 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 the water.

from The Century Dictionary.

• noun A popular name of the Cetorhinus maximus (or Selache maxima), one of the largest of the sharks.

from the GNU version of the Collaborative International Dictionary of English.

• (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.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun 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.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun large harmless plankton-eating northern shark; often swims slowly or floats at the sea surface