- hammerhead, hammerhead shark - medium-sized live-bearing shark with eyes at either end of a flattened hammer-shaped head; worldwide in warm waters; can be dangerous
--1 is a kind of shark
--1 is a member of Sphyrna, genus Sphyrna
--1 has particulars:smooth hammerhead, Sphyrna zygaena; smalleye hammerhead, Sphyrna tudes; shovelhead, bonnethead, bonnet shark, Sphyrna tiburo