The Collaborative International Dictionary of English v.0.48:

Stegnosis \Steg*no"sis\ (st[e^]g*n[=o]"s[i^]s), n. [NL., fr. Gr.
   ste`gnwsis. See Stegnotic.] (Med.)
   Constipation; also, constriction of the vessels or ducts.
   [1913 Webster]