The Collaborative International Dictionary of English v.0.48:

Impone \Im*pone"\, v. t. [L. imponere, impositum, to place upon;
   pref. im- in + ponere to place. See Position.]
   To stake; to wager; to pledge. [Obs.]
   [1913 Webster]

         Against the which he has imponed, as I take it, six
         French rapiers and poniards.             --Shak.
   [1913 Webster]