Definition of killer whale
: a relatively small toothed whale (Orcinus orca of the family Delphinidae) that is black above with white underparts and white oval-shaped patches behind the eyes, attains a length of 20 to 30 feet (6 to 9 meters), typically hunts in groups, and preys chiefly on sea mammals (such as seals, sea lions, and other whales), large fish, and squid — called also
orca
