dolphin (n.) Look up dolphin at Dictionary.com
mid-14c., from Old French daulphin, from Medieval Latin dolfinus, from Latin delphinus "dolphin," from Greek delphis (genitive delphinos) "dolphin," related to delphys "womb," perhaps via notion of the animal bearing live young, or from its shape, from PIE *gwelbh-. Popularly applied to the dorado from late 16c.