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[si-tey-shuh n] /sɪˈteɪ ʃən/
belonging to the Cetacea, an order of aquatic, chiefly marine mammals, including the whales and dolphins.
a cetacean mammal.
1830-40; < New Latin Cetace(a) name of the order (see cet-, -acea) + -an
Related forms
cetaceous, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for cetaceans
  • The resort's location near mangrove estuaries attracts the cetaceans for which it is named.
  • Roughly speaking, these animals filled the ecological niches now occupied by toothed cetaceans such as dolphins and killer whales.
  • Most would defend their country's right to harpoon cetaceans to the edge of extinction.
  • Everything from manhole covers to signs in the town hall is decorated with the cetaceans.
  • It is not clear whether cetaceans undergo dream sleep.
  • The really peculiar thing about these cetaceans is that only the adult males have backward fins.
  • One wonders how bats and cetaceans perceive sound images.
  • For whales and other cetaceans, apparently, an important aid has been well-developed ears.
  • The cetaceans also have a higher ethical consciousness.
  • cetaceans have a simplified version missing several proteins, and it still works.
British Dictionary definitions for cetaceans


of, relating to, or belonging to the Cetacea, an order of aquatic placental mammals having no hind limbs and a blowhole for breathing: includes toothed whales (dolphins, porpoises, etc) and whalebone whales (rorquals, right whales, etc)
a whale
Word Origin
C19: from New Latin Cētācea, ultimately from Latin cētus whale, from Greek kētos
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for cetaceans



1836, from Cetacea, name of the order of marine mammals, + -an. As an adjective from 1839.

Online Etymology Dictionary, © 2010 Douglas Harper
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cetaceans in Science
Any of various, often very large aquatic mammals of the order Cetacea, having a hairless body that resembles that of a fish. Cetaceans have an elongated skull, a flat, horizontal tail, forelimbs modified into broad flippers, and no hind limbs. They breathe through blowholes located usually at the top of the skull. Whales, dolphins, and porpoises are cetaceans. See more at baleen whale, toothed whale.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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