A boxfish; (later) specifically one of the genus Ostracion. Now only (in form Ostracion): the genus itself.
Valid publication of the genus name: Linnaeus Systema Naturae (ed. 10, 1758) I. 330.
Mid 17th century; earliest use found in Thomas Browne (1605–1682), physician and author. From post-classical Latin ostracion (Gesner 1558) from Hellenistic Greek ὀστράκιον shellfish, in ancient Greek small earthen vessel from ancient Greek ὄστρακον + -ιον, diminutive suffix.