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[om-uh-tid-ee-uh m] /ˌɒm əˈtɪd i əm/
noun, plural ommatidia
[om-uh-tid-ee-uh] /ˌɒm əˈtɪd i ə/ (Show IPA).
one of the radial elements composing a compound eye.
1880-85; < New Latin < Greek ommat- (stem of ómma eye) + New Latin -idium -idium
Related forms
ommatidial, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for ommatidium
  • The compound eyes are either completely divided into dorsal and ventral eyes or are joined by one ommatidium.
British Dictionary definitions for ommatidium


noun (pl) -tidia (-ˈtɪdɪə)
any of the numerous cone-shaped units that make up the compound eyes of some arthropods
Derived Forms
ommatidial, adjective
Word Origin
C19: via New Latin from Greek ommatidion, from omma eye
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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ommatidium in Science
Plural ommatidia
One of the tiny light-sensitive parts of the compound eye of insects and other arthropods. An ommatidium resembles a single simplified eye. See more at compound eye.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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