The Collaborative International Dictionary of English v.0.48:

Scissure \Scis"sure\, n. [L. scissura, from scindere, scissum,
   to cut, split.]
   A longitudinal opening in a body, made by cutting; a cleft; a
   fissure. --Hammond.
   [1913 Webster]

WordNet (r) 3.0 (2006):

scissure
    n 1: a long narrow opening [syn: crack, cleft, crevice,
         fissure, scissure]