Real Dictionary

mallet
countable noun: A mallet is a wooden hammer with a square head.

mallet in American English
a kind of hammer, usually with a heavy wooden head and a short handle, for driving a chisel, etc.
noun: a hammerlike tool with a head commonly of wood but occasionally of rawhide, plastic, etc., used for driving any tool with a wooden handle, as a chisel, or for striking a surface

mallet in British English
noun: a tool resembling a hammer but having a large head of wood, copper, lead, leather, etc, used for driving chisels, beating sheet metal, etc