hammerhead

Short definition from Wiktionary

Noun

1. 1
   The portion of a hammer containing the metal striking face (also including the claw or peen if so equipped).
2. 2
   Any organism with head shaped like that of a hammer: Any shark of the family Sphyrnidae, which only includes the genera Sphyrna and Zygaena, with eyes set on projections from the sides of the head.
3. 3
   Any organism with head shaped like that of a hammer: A hogsucker, a fresh-water fish of species Hypentelium nigricans, in the sucker family Catostomidae.
4. 4
   Any organism with head shaped like that of a hammer: A hammer-headed fruit bat, a fruit bat of species Hypsignathus monstrosus, with a large blunt nozzle.
5. 5
   Any organism with head shaped like that of a hammer: A hammerkop, a bird of species Scopus umbretta.
6. 6
   A stupid person, a dunce.
7. 7
   A turn-around; a parking area constructed in a subdivision for initial access and construction.
8. 8
   A kind of ribozyme; hammerhead ribozyme.