What is "stirrup bone"

Stirrup \Stir"rup\, n. [OE. stirop, AS. stigr[=a]p; st[=i]gan to mount, ascend + r[=a]p a rope; akin to G. stegreif a stirrup.

1. 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.

   Our host upon his stirpoes stood anon.
   --Chaucer.

2. (Carp. & Mach.) Any piece resembling in shape the stirrup of a saddle, and used as a support, clamp, etc. See Bridle iron.

3. (Naut.) A rope secured to a yard, with a thimble in its lower end for supporting a footrope.
   --Totten.

   Stirrup bone (Anat.), the stapes.

   Stirrup cup, a parting cup taken after mounting.

   Stirrup iron, an iron stirrup.

   Stirrup leather, or Stirrup strap, the strap which attaches a stirrup to the saddle. See Stirrup, 1.

n. (context anatomy English) the smallest bone in the human body; it is situated in the ear and passes vibrations from the anvil to cochlea