An eel-like fish of the genus Ophidion (or Ophidium), or (formerly) of the family Ophidiidae; a cusk-eel.
Valid publication of the genus name Ophidion: Linnaeus Systema Naturae (ed. 10, 1758) I. 259. Linnaeus later emended the form to Ophidium (Systema Naturae (ed. 12, 1766) I. 431), but by the rules of taxonomic nomenclature this has reverted to Ophidion.
Early 18th century; earliest use found in Phillips's New World of Words. From classical Latin ophīdion a small fish resembling the conger (Pliny) from ancient Greek ὀϕίδιον small snake from ὄϕις serpent + -ίδιον.