noun
(biology, countable) Any of various primitive light-sensitive organs or regions in many diverse organisms.
(countable) An eye-like marking on the tail of a peacock or the wing of a butterfly.
(botany, countable) A coloured spot in a motile gamete or spore, which is sensitive to light.
(botany) Any of a group of fungal infections of grasses that are characterized by oval spots; strawbreaker.