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[kloh-ey-kuh] /kloʊˈeɪ kə/
noun, plural cloacae
[kloh-ey-see] /kloʊˈeɪ si/ (Show IPA)
  1. the common cavity into which the intestinal, urinary, and generative canals open in birds, reptiles, amphibians, many fishes, and certain mammals.
  2. a similar cavity in invertebrates.
a sewer, especially an ancient sewer.
Origin of cloaca
1650-60; < Latin clo(u)āca, cluāca sewer, drain; probably akin to Greek klýzein to wash, wash away
Related forms
cloacal, adjective
precloacal, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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British Dictionary definitions for cloaca


noun (pl) -cae (-kiː)
a cavity in the pelvic region of most vertebrates, except higher mammals, and certain invertebrates, into which the alimentary canal and the genital and urinary ducts open
a sewer
Derived Forms
cloacal, adjective
Word Origin
C18: from Latin: sewer; related to Greek kluzein to wash out
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 cloaca

1650s, euphemism for "underground sewer," from Latin cloaca "public sewer, drain," from cluere "to cleanse," from PIE root *kleue- "to wash, clean" (cf. Greek klyzein "to dash over, wash off, rinse out," klysma "liquid used in a washing;" Lithuanian šluoju "to sweep;" Old English hlutor, Gothic hlutrs, Old High German hlutar, German lauter "pure, clear"). Use in biology, in reference to eliminatory systems of lower animals, is from 1834. Related: Cloacal (1650s); cloacinal (1857).

Online Etymology Dictionary, © 2010 Douglas Harper
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cloaca in Medicine

cloaca clo·a·ca (klō-ā'kə)

  1. In early embryos, the entodermally lined chamber into which the hindgut and allantois empty.

  2. The common cavity into which the intestinal, genital, and urinary tracts open in vertebrates such as fish, reptiles, birds, and some mammals.

  3. An opening in a diseased bone containing a fragment of dead bone.

clo·a'cal (-kəl) adj.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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cloaca in Science
Plural cloacae (klō-ā'sē')
  1. The body cavity into which the intestinal, urinary, and genital canals empty in birds, reptiles, amphibians, most fish, and monotremes. The cloaca has an opening for expelling its contents from the body, and in females it serves as the depository for sperm. Also called vent.

  2. See vent.

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