noun (n)

• support consisting of metal loops into which rider's feet go(noun.artifact)

  Synonym:
  stirrup iron
  

  source: wordnet30
• the stirrup-shaped ossicle that transmits sound from the incus to the cochlea(noun.body)

  Synonym:
  stapes
  

  source: wordnet30
• 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.(noun)

  source: webster1913