The portion of a hammer containing the metal striking face (also including the claw or peen if so equipped).
(zoology) Any of various sharks of the genus Sphyrna or Zygaena having the eyes set on projections from the sides of the head, which gives it a hammer shape.
(zoology) A fresh-water fish; the , in the minnow family Cyprinidae.
(zoology) An African fruit bat, the , , so called from its large blunt nozzle.
(slang) A stupid person, a dunce.
1960:butler joined us with a telegram for Bobbie on a salver. From her mother, I presumed, calling me some name which she had forgotten to insert in previous communications. Or, of course, possibly expressing once more her conviction that I was a guffin, which, I thought, having had time to ponder over it, would be something in the nature of a bohunkus or a hammerhead. (P. G. Wodehouse, Jeeves in the Offing, chapter V)
