- any of several fishes of the family Diodontidae, especially Diodon hystrix, of tropical seas, capable of inflating the body with water or air until it resembles a globe, with erection of the long spines covering the skin.
- any of various plectognath fishes of the genus Diodon and related genera, of temperate and tropical seas, having a body that is covered with sharp spines and can be inflated into a globe: family Diodontidae
