Hammer  —n. 1 a tool with a heavy metal head at right angles to its handle, used for driving nails etc. B similar device, as for exploding the charge in a gun, striking the strings of a piano, etc. 2 auctioneer's mallet. 3 metal ball attached to a wire for throwing in an athletic contest. —v. 1 a hit or beat with or as with a hammer. B strike loudly. 2 a drive in (nails) with a hammer. B fasten or secure by hammering (hammered the lid down). 3 (usu. Foll. By in) inculcate (ideas, knowledge, etc.) Forcefully or repeatedly. 4 colloq. Defeat utterly; beat up. 5 (foll. By at, away at) work hard or persistently at.  come under the hammer be sold at auction. Hammer out 1 make flat or smooth by hammering. 2 work out details of (a plan etc.) Laboriously. 3 play (a tune, esp. On the piano) loudly or clumsily.  hammering n. (esp. In sense 4 of v.). [old english]