Definition of mule

• n. - A hybrid animal; specifically, one generated between an ass and a mare, sometimes a horse and a she-ass. See Hinny.
• n. - A plant or vegetable produced by impregnating the pistil of one species with the pollen or fecundating dust of another; -- called also hybrid.
• n. - A very stubborn person.
• n. - A machine, used in factories, for spinning cotton, wool, etc., into yarn or thread and winding it into cops; -- called also jenny and mule-jenny.