pinniped (n.) Look up pinniped at Dictionary.com
1842, from Modern Latin Pinnipedia, suborder of aquatic carnivorous mammals (seals and walruses), literally "having feet as fins," from Latin pinna in secondary sense "fin" (see pin (n.)) + pes, genitive pedis "foot," from PIE root *ped- (1) "a foot" (see foot (n.)).