The Collaborative International Dictionary of English v.0.48:

Unperfect \Un*per"fect\, a. [Pref. un- + perfect.]
   Imperfect. [Obs.] --Holland. -- Un*per"fect*ly, adv. [Obs.]
   --Hales. -- Un*per"fect*ness, n. [Obs.]
   [1913 Webster]