Con*vict"ive*ness

from The Collaborative International Dictionary of English v.0.48

Convictive \Con*vict"ive\, a.
   Convincing. [R.]
   [1913 Webster]

         The best and most convictive argument.   --Glanwill.
   -- {Con*vict"ive*ly}, adv. -- {Con*vict"ive*ness}, n.
   [1913 Webster]