Stirup or Stirrup: How To spell?

The word Stirup is misspelled against Stirrup, a verb meaning "A kind of ring, or bent piece of metal, wood, leather, or the like, horizontal in one part for receiving the foot of a rider, and attached by a strap to the saddle, -- used to assist a person in mounting a horse, and to enable him to sit steadily in riding, as well as to relieve him by supporting a part of the weight of the body."