Facet

Definition

One of the numerous small, flat surfaces on the compound eyes of insects and some other arthropods, which individually capture light to contribute to the overall image perceived by the organism.

Etymology

From the French word 'facette', a diminutive of 'face', meaning a small face or surface.

Example

The dragonfly's compound eyes are composed of thousands of tiny facets, each acting as a separate photoreceptive unit.

Synonyms

• Facet

Related Terms

• Compound eye
• Photoreceptor
• Arthropod
• Ommatidium

Usage Notes

Facets are essential for an insect's vision, allowing it to detect motion and form images by combining inputs from multiple photoreceptive units (ommatidia).