1. A simple eye or eye-like structure found in invertebrates, consisting of a single lens or light-sensitive cell cluster.
Usage: biology; plural: ocelli
2. A small, rounded spot or marking resembling an eye, especially on the wings of butterflies or other insects.
Usage: biology; plural: ocelli

Examples

• The fruit fly has three ocelli arranged in a triangle on top of its head.
• Insects like bees use their ocelli to detect light and maintain orientation during flight.
• The peacock butterfly displays prominent ocelli on its wings as a defense mechanism.
• Each ocellus on the moth's wing is a dark spot surrounded by lighter rings.
• Unlike compound eyes, an ocellus cannot form detailed images but senses brightness changes.