Noun
white-sided dolphin (plural white-sided dolphins)
Either of two dolphins of the genus Lagenorhynchus which have conspicuous white markings on the sides of the body: Lagenorhynchus acutus in the North Atlantic (the Atlantic white-sided dolphin), and Lagenorhynchus obliquidens in the North Pacific (the Pacific white-sided dolphin). [from 19th c.]