Source : Webster's Revised Unabridged Dictionary (1913)

Perfectibility \Per*fect`i*bil"i*ty\, n. [Cf. F.
   perfectibilit['e].]
   The quality or state of being perfectible.

Source : WordNet®

perfectibility
     n : the capability of becoming perfect; "he believes in the
         ultimate perfectability of man" [syn: {perfectability}]
         [ant: {imperfectibility}]