Source : Webster's Revised Unabridged Dictionary (1913)

Stridor \Stri"dor\, n. [L., from stridere to make any harsh,
   grating, or creaking sound.]
   A harsh, shrill, or creaking noise. --Dryden.

Source : WordNet®

stridor
     n : a whistling sound when breathing (usually heard on
         inspiration); indicates obstruction of the trachea or
         larynx