• synonyms


noun Biochemistry.
  1. a nitrogen-containing polysaccharide, related chemically to cellulose, that forms a semitransparent horny substance and is a principal constituent of the exoskeleton, or outer covering, of insects, crustaceans, and arachnids.
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Origin of chitin

1830–40; < French chitine < Greek chit(ṓn) tunic, chiton + French -ine -in2
Related formschi·tin·ous, chi·tin·oid, adjective
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for chitinous

Historical Examples

  • Armatus: set with spines, claws or other chitinous processes.

    Explanation of Terms Used in Entomology

    John. B. Smith

  • Scutes: the chitinous shields or plates on the segments of larvae.

  • The chitinous covering of this harvesting-ant is firm and hard.

  • The chitinous object he had picked up now shook and quivered of itself.

    Nightmare Planet

    Murray Leinster

  • The uneasy rustling of chitinous arms against white robes recalled him from his meditation.

    The Worshippers

    Damon Francis Knight

British Dictionary definitions for chitinous


  1. a polysaccharide that is the principal component of the exoskeletons of arthropods and of the bodies of fungi
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Derived Formschitinous, adjectivechitinoid, adjective

Word Origin

C19: from French chitine, from Greek khitōn chiton + -in
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

Word Origin and History for chitinous



1836, from French chitine, from Greek khiton "frock, tunic," of soldiers, "coat of mail," used metaphorically for "any coat or covering." "Probably an Oriental word" [Liddell & Scott]. Klein compares Hebrew kuttoneth, Aramaic kittana, Arabic kattan "linen."

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Online Etymology Dictionary, © 2010 Douglas Harper

chitinous in Medicine


  1. A tough, protective, semitransparent polysaccharide forming the principal component of arthropod exoskeletons and the cell walls of certain fungi.
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Related formschitin•ous adj.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

chitinous in Science


  1. A tough, semitransparent substance that is the main component of the exoskeletons of arthropods, such as the shells of crustaceans and the outer coverings of insects. Chitin is also found in the cell walls of certain fungi and algae. Chemically, it is a nitrogenous polysaccharide (a carbohydrate).
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The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.