Definition of hammerhead

• n. - A shark of the genus Sphyrna or Zygaena, having the eyes set on projections from the sides of the head, which gives it a hammer shape. The Sphyrna zygaena is found in the North Atlantic. Called also hammer fish, and balance fish.
• n. - A fresh-water fish; the stone-roller.
• n. - An African fruit bat (Hypsignathus monstrosus); -- so called from its large blunt nozzle.