Mule :  (noun)
1: sterile offspring of a male donkey and a female horse
2: a slipper that has no fitting around the heel [syn: mules, scuff, scuffs]

Cape Colored, Eurasian, Siberian husky, ass, bastard, beast of burden, bigot, bitter-ender, bullethead, camel, cattalo, citrange, cross, crossbred, crossbreed, diehard, dogmatist, donkey, draft animal, dromedary, elephant, fanatic, griffe, half blood, half-bred, half-breed, half-caste, hardnose, high yellow, hinny, horse, husky, hybrid, intransigeant, intransigent, jennet, jenny, ladino, last-ditcher, liger, llama, malamute, manlike, manly, masculine, maverick, mestee, mestiza, mestizo, metis, metisse, mixblood, mixed-blood, mongrel, mulatto, mustee, octoroon, ox, pack horse, perverse fool, pighead, plumcot, positivist, purist, quadroon, quintroon, reindeer, sambo, silkworm, sledge dog, spider, spinner, spinning frame, spinning jenny, spinster, standpat, standpatter, stickler, sumpter, sumpter horse, sumpter mule, tangelo, throstle, tigon, zebrass, zebrule,