noun

1. a tool for pounding, usually consisting of a metal head fastened across one end of a handle: one end of the head may be a pronged claw for pulling nails
2. a thing like this tool in shape or use; specif.,
   1. the mechanism that strikes the firing pin or percussion cap in a firearm
   2. a device for striking a bell, gong, metal bar, etc. to make a sound
   3. any of the felt-covered mallets that strike against the strings of a piano
   4. a high-speed, hammering power tool fitted with a metal block or chisel, for shaping metal, breaking up paved surfaces, etc.
3. the malleus, one of the three bones of the middle ear
4. an auctioneer's gavel
5. a metal ball weighing usually sixteen pounds, hung from a wire handle and thrown for distance in a track-and-field competition

Etymology: ME hamer < OE hamor, akin to Ger hammer, ON hamarr, crag, cliff < IE *omor-, stone hammer < base *ak-m- < a-, sharp, sharp stone > Gr akmē, point, akmōn, anvil

transitive verb

1. to strike repeatedly with or as with a hammer
2. to make or fasten with a hammer
3. to drive, force, or shape with or as with hammer blows to hammer an idea into someone's head

intransitive verb