The Collaborative International Dictionary of English v.0.48:
Perforce \Per*force"\, adv. [F. par (L. per) + force.] By force; of necessity; at any rate. --Shak. [1913 Webster]The Collaborative International Dictionary of English v.0.48:
Perforce \Per*force"\, v. t. To force; to compel. [Obs.] [1913 Webster]WordNet (r) 3.0 (2006):
perforce adv 1: by necessity; by force of circumstance