Diodon \Di"o*don\, n. [Gr. di- = di`s- twice + ?, ?, a tooth: cf. F. diodon.] 1. (Zo["o]l.) A genus of spinose, plectognath fishes, having the teeth of each jaw united into a single beaklike plate. They are able to inflate the body by taking in air or water, and, hence, are called {globefishes}, {swellfishes}, etc. Called also {porcupine fishes}, and {sea hedgehogs}. 2. (Zo["o]l.) A genus of whales.