noun, plural om·ma·tid·i·a [om-uh-tid-ee-uh] /ˌɒm əˈtɪd i ə/. Zoology.
one of the radial elements composing a compound eye.
Origin of ommatidium
1880–85;Related formsom·ma·tid·i·al, adjective
< New Latin
< Greek ommat-
(stem of ómma
eye) + New Latin -idium -idium
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for ommatidia
Historical Examples of ommatidia
These are in some genera like the single elements (ommatidia) of a compound insect eye, in others like simple ocelli.
It shows in Scorpio and Limulus a tendency to segregate into minor groups or “ommatidia.”
The compound eye of the king-crab (Limulus) is the only recognized instance of ommatidia in their simplest state.
Fenestrate membrane: of the compound eye is at the base of the ommatidia, at their junction with the optic nerve; see retina.
The retinal portion is composed of a corresponding number of ocular units or ommatidia.
British Dictionary definitions for ommatidia
noun plural -tidia (-ˈtɪdɪə)
Derived Formsommatidial, adjective
any of the numerous cone-shaped units that make up the compound eyes of some arthropods
Word Origin for ommatidium
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
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 © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.