Source : Webster's Revised Unabridged Dictionary (1913)

Rammer \Ram"mer\, n.
   One who, or that which, rams or drives. Specifically:
   (a) An instrument for driving anything force; as, a rammer
       for driving stones or piles, or for beating the earth to
       more solidity.
   (b) A rod for forcing down the charge of a gun; a ramrod.
   (c) (Founding) An implement for pounding the sand of a mold
       to render it compact.

Source : WordNet®

rammer
     n : a tool for driving something with force