ommatidium

From Ancient Greek ὀμματίδιον (ommatídion, “little eye”), equivalent to ὄμμα (ómma, stem ὄμματ-) + -idium.

• (UK) IPA^(key): /ɒməˈtɪdɪəm/
• (Canada) IPA^(key): /ɑməˈtɪdɪəm/

ommatidium (plural ommatidia)

1. (zoology) One of the conical substructures which make up the eyes of invertebrates with compound eyes.
   • 1996, Michael J. Roberts, Spiders of Britain and Northern Europe, Collins, published 1996, page 12:

     The ‘compound’ eyes of insects [...] are made up of large numbers of facets or ommatidia, and in this sense, our own eyes are ‘simple’.

From Ancient Greek ὀμματίδιον (ommatídion), diminutive of ὄμμα (ómma, “eye”).

• (Classical Latin) IPA^(key): [ɔm.maˈtɪ.di.ũː]
• (modern Italianate Ecclesiastical) IPA^(key): [om.maˈt̪iː.d̪i.um]

ommatidium n (genitive ommatidiī or ommatidī); second declension

1. ommatidium

Second-declension noun (neuter).

¹Found in older Latin (until the Augustan Age).

• aumātium