Their name , dolphin , comes from the Ancient Greek Î Î Î '' Ï Î Ï ( delphis ) meaning `` with a womb '' , because it was first thought to be a fish with a womb . The animal 's name can therefore be interpreted as meaning `` a ` fish ' with a womb '' . The name was transmitted via the Latin delphinus ( the romanization of the later Greek Î Î Î '' Ï á -- Î 1\/2 Î Ï - delphinos ) , which in Middle Latin became dolfinus and in Old French daulphin , which reintroduced the ph into the word .