Is it ensure, insure, or assure?
1872, Modern Latin, from Greek stenosis "narrowing," from stenoun "to narrow," from stenos "narrow."
stenotic ste·not·ic (stə-nŏt'ĭk)
Of or affected with stenosis.
stenosis ste·no·sis (stə-nō'sĭs)
n. pl. ste·no·ses (-sēz)
A constriction or narrowing of a duct or passage; a stricture.