whitetip shark n 1: smooth dogfish of Pacific and Indian Oceans and Red Sea having white-tipped dorsal and caudal fins [syn: {whitetip shark}, {reef whitetip shark}, {Triaenodon obseus}] 2: large deep-water shark with white-tipped dorsal fin; worldwide distribution; most dangerous shark [syn: {whitetip shark}, {oceanic whitetip shark}, {white-tipped shark}, {Carcharinus longimanus}]