noun, plural om·ma·tid·i·a [om-uh-tid-ee-uh] /ˌɒm əˈtɪd i ə/. Zoology.
Origin of ommatidium
Examples from the Web for ommatidia
Fenestrate membrane: of the compound eye is at the base of the ommatidia, at their junction with the optic nerve; see retina.Explanation of Terms Used in Entomology|John. B. Smith
It shows in Scorpio and Limulus a tendency to segregate into minor groups or “ommatidia.”
The retinal portion is composed of a corresponding number of ocular units or ommatidia.
These are in some genera like the single elements (ommatidia) of a compound insect eye, in others like simple ocelli.
The compound eye of the king-crab (Limulus) is the only recognized instance of ommatidia in their simplest state.