mule Meaning, Definition & Usage

  1. noun hybrid offspring of a male donkey and a female horse; usually sterile
  2. noun a slipper that has no fitting around the heel
    scuff.

WordNet

Mule noun
Etymology
F., a she-mule, L. mula, fem. of mulus; cf. Gr. , . Cf. AS. ml, fr. L. mulus. Cf. Mulatto.
Definitions
  1. (Zoöl.) A hybrid animal; specifically, one generated between an ass and a mare, sometimes a horse and a she-ass. See Hinny. ✍ Mules are much used as draught animals. They are hardy, and proverbial for stubbornness.
  2. (Bot.) A plant or vegetable produced by impregnating the pistil of one species with the pollen or fecundating dust of another; -- called also hybrid.
  3. A very stubborn person.
  4. 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.

Webster 1913