English This entry needs a photograph or drawing for illustration. Please try to find a suitable image on Wikimedia Commons or upload one there yourself! Etymology From long + fin. English Wikipedia has an article on:longfinWikipedia Noun longfin (plural longfins) Any member of the family Plesiopidae of elongated perciform fish. Synonyms roundhead, spiny basslet Derived terms longfin burrower longfin perch (Caprodon longimanus) longfin pilot whale Translations a fish species Maori: mātā Wikiwand - on Seamless Wikipedia browsing. On steroids.