The crossword solution for the term 'porpoise cousin' is 'ORCA'. Orcas, also known as killer whales, are the largest member of the dolphin family and are closely related to porpoises. They are found in all oceans around the world and are easily recognizable by their distinctive black and white markings. Orcas are highly intelligent and social animals, living in large pods and communicating with each other through a complex system of vocalizations.