(1):

(n.) An instrument for driving anything with force; as, a rammer for driving stones or piles, or for beating the earth to more solidity

(2):

(n.) One who, or that which, rams or drives.

(3):

(n.) An implement for pounding the sand of a mold to render it compact.

(4):

(n.) A rod for forcing down the charge of a gun; a ramrod