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[ep-uh-thee-lee-uh m] /ˌɛp əˈθi li əm/
noun, plural epitheliums, epithelia
[ep-uh-thee-lee-uh] /ˌɛp əˈθi li ə/ (Show IPA).
any animal tissue that covers a surface, or lines a cavity or the like, and that, in addition, performs any of various secretory, transporting, or regulatory functions.
1740-50; < New Latin < Greek epi- epi- + thēl() teat + New Latin -ium -ium
Related forms
epithelial, adjective
interepithelial, adjective
nonepithelial, adjective
subepithelial, adjective
unepithelial, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for epithelial
  • Behind the epithelial lining of the foramen the choroid plexuses of the lateral ventricles are joined across the middle line.
  • The tube is lined by entoderm from which the epithelial lining of the respiratory tract is developed.
  • She isolated potentially cancerous cells, known as epithelial cells.
  • Nerve cells are modified epithelial cells, organs do not originate from these cells.
  • Major problems start to happen, however, once bacteria get through that epithelial barrier and into the tissues of your body.
  • When a salamander loses a leg, specialized epithelial cells cover the wound, forming a multilayered structure.
British Dictionary definitions for epithelial


noun (pl) -liums, -lia (-lɪə)
an animal tissue consisting of one or more layers of closely packed cells covering the external and internal surfaces of the body. The cells vary in structure according to their function, which may be protective, secretory, or absorptive
Derived Forms
epithelial, adjective
Word Origin
C18: New Latin, from epi- + Greek thēlē nipple
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Word Origin and History for epithelial



1748, Modern Latin (Frederick Ruysch), from Greek epi "upon" (see epi-) + thele "teat, nipple" (see fecund). Related: Epithelial.

Online Etymology Dictionary, © 2010 Douglas Harper
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epithelial in Medicine

epithelium ep·i·the·li·um (ěp'ə-thē'lē-əm)
n. pl. ep·i·the·li·ums or ep·i·the·li·a (-lē-ə)
Membranous tissue composed of one or more layers of cells separated by very little intercellular substance and forming the covering of most internal and external surfaces of the body and its organs.

ep'i·the'li·al 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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epithelial in Science
Plural epithelia
The thin, membranous tissue that lines most of the internal and external surfaces of an animal's body. Epithelium is composed of one or more layers of densely packed cells. In vertebrates, it lines the outer layer of the skin (epidermis), the surface of most body cavities, and the lumen of fluid-filled organs, such as the gut or intestine.

epithelial adjective
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Article for epithelial


in anatomy, layer of cells closely bound to one another to form continuous sheets covering surfaces that may come into contact with foreign substances. Epithelium occurs in both plants and animals

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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