Definition of: hammer

(ham′ər) noun
1. A hand implement with a head at right angles to the handle, used for driving nails, pounding, swaging, etc. See under CLAW HAMMER, TACK HAMMER.
2. A machine, as a steam hammer or trip hammer, performing functions similar to those of a heavy hand hammer.
3. A part or piece of a machine or apparatus performing functions similar to those of a hammer: especially, the piece by which a gong or the like is struck.
4. That part of a gunlock which strikes the cap or cartridge.
5. A padded piece that strikes the string of a pianoforte.
6. An auctioneer's mallet.
7. A lever in an internal combustion engine which controls the exhaust.
8. Anat. The malleus of the middle ear.
9. A metal ball weighing 16 pounds with a long wire or wooden handle: used for throwing in track meets.
—under the hammer For sale at auction.
—v.t.
1. To strike or beat with or as with a hammer; drive, as a nail.
2. To shape or fasten with a hammer.
3. To form or force as if with hammer blows: to hammer an idea into his head.
—v.i.
4. To strike blows with or as with a hammer. [OE hamer]
—ham′mer·er noun