The Collaborative International Dictionary of English v.0.48:

Adeption \A*dep"tion\, n. [L. adeptio. See Adept, a.]
   An obtaining; attainment. [Obs.]
   [1913 Webster]

         In the wit and policy of the capitain consisteth the
         chief adeption of the victory.           --Grafton.
   [1913 Webster]