The Collaborative International Dictionary of English v.0.48:

Deforciant \De*for"ciant\, n. [OF. deforciant, p. pr. of
   deforcier. See Deforce.] (Eng. Law)
   (a) One who keeps out of possession the rightful owner of an
       estate.
   (b) One against whom a fictitious action of fine was brought.
       [Obs.] --Burrill.
       [1913 Webster]