Definition of "mule"
A generally sterile male or female hybrid offspring of a male donkey and a female horse.
A generally sterile hybrid offspring of any two species of animals.
A stubborn person.
A person paid to smuggle drugs.
A coin or medal minted with obverse and reverse designs not normally seen on the same piece, either intentionally or in error.
A character on an MMORPG used mainly to store extra inventory of the owner's primary character.
A shoe that has no fitting or strap around the heel, but which covers the foot.