or·ca (ôr?k?)n. A black-and-white toothed whale (Orcinus orca) that feeds on large fish, squid, and marine mammals such as seals and other whales and dolphins. Also called killer whale.[Latin ?rca, whale, probably alteration (probably influenced by ?rca, vessel) of Greek orux, orug-, pickaxe, a kind of large fish or whale, perhaps from orussein, to dig.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.orca (???k?) n, pl orcas or orca1. (Animals) a killer whale[C20: Latin]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014kill?er whale? n. a large, predatory, black-and-white dolphin, Orcinus orca. [1880?85] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.or·ca (ôr?k?) A large dolphin found in all the world’s oceans, having a black body with a white underside and a tall, triangular dorsal fin. Orcas grow up to 30 feet (9.1 meters) in length. Also called killer whale.The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.