The Collaborative International Dictionary of English v.0.48:

Scission \Scis"sion\, n. [L. scissio, fr. scindere, scissum, to
   cut, to split: cf. F. scission.]
   The act of dividing with an instrument having a sharp edge.
   --Wiseman.
   [1913 Webster]

WordNet (r) 3.0 (2006):

scission
    n 1: the act of dividing by cutting or splitting

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "scission":
   abscission, amputation, butchering, chopping, cleavage, cutting,
   dichotomy, enucleation, excision, fission, laceration, mutilation,
   rending, resection, ripping, section, severance, slashing, slicing,
   splitting, surgery, tearing