The Collaborative International Dictionary of English v.0.48:

Stenosis \Ste*no"sis\, n. [NL., fr. Gr. steno`s narrow.] (Med.)
   A narrowing of the opening or hollow of any passage, tube, or
   orifice; as, stenosis of the pylorus. It differs from
   stricture in being applied especially to diffused rather than
   localized contractions, and in always indicating an origin
   organic and not spasmodic.
   [1913 Webster]

WordNet (r) 3.0 (2006):

stenosis
    n 1: abnormal narrowing of a bodily canal or passageway [syn:
         stenosis, stricture]