1. The head of a hammer.

2. Any of several predatory sharks of the genus Sphyrna, having the sides of the head elongated into fleshy extensions with the eyes at the ends.

3. A wading bird (Scopus umbretta) of Africa and Arabia, having brown plumage, a large bladelike bill, and a long backward-pointing crest. Also called hamerkop.

4. An African fruit bat (Hypsignathus monstrosus), the male of which has a distinctive enlarged head.