om·​ma·​tid·​i·​um | \ ˌä-mə-ˈti-dē-əm How to pronounce ommatidium (audio) \
plural ommatidia\ ˌä-​mə-​ˈti-​dē-​ə How to pronounce ommatidia (audio) \

Definition of ommatidium

: one of the elements corresponding to a small simple eye that make up the compound eye of an arthropod

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Other Words from ommatidium

ommatidial \ ˌä-​mə-​ˈti-​dē-​əl How to pronounce ommatidial (audio) \ adjective

Examples of ommatidium in a Sentence

Recent Examples on the Web The tiny organ contains 100 ommatidia, or subunits that make up compound eyes found today in many insects, surrounding a light-sensing structure called a rhabdom. Jason Daley, Smithsonian, "Gaze Into a 530-Million-Year-Old Eye, the Oldest Yet Discovered," 11 Dec. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'ommatidium.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of ommatidium

1884, in the meaning defined above

History and Etymology for ommatidium

New Latin, from Greek ommat-, omma eye; akin to Greek ōps eye — more at eye

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Time Traveler for ommatidium

Time Traveler

The first known use of ommatidium was in 1884

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Cite this Entry

“Ommatidium.” Dictionary, Merriam-Webster, Accessed 13 Aug. 2020.

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