ommatidium

This term is a specialized biological descriptor used almost exclusively in entomology and zoology. It describes the structural unit of a compound eye, emphasizing the modular nature of arthropod vision where each unit captures a small portion of the visual field.

Because it is a technical term derived from Greek, it follows a Latinized pluralization pattern. The singular form ends in -ium, which transforms to -ia in the plural, a common characteristic of anatomical and scientific terminology.