Pronunciation: (stā'pēz),[key] —n., —pl.sta•pes, sta•pe•desPronunciation: (stu-pē'dēz).[key]Anat. the innermost, stirrup-shaped bone of a chain of three small bones in the middle ear of humans and other mammals, involved in the conduction of sound vibrations to the inner ear. Also called stirrup. Cf. incus (def. 1), malleus. See diag. under ear.