Any of various marine mammals of the order Cetacea, including the whales, dolphins, and porpoises, having the general shape of a fish with forelimbs modified to form flippers, a tail with horizontal flukes, and one or two blowholes for breathing.
[From New Latin Cētācea, order name, from Latin cētus, whale; see CETUS.]
ce·tacean, ce·taceous (-shəs) adj.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.