The Collaborative International Dictionary of English v.0.48:

Compulsatory \Com*pul"sa*to*ry\, a.
   Operating with force; compelling; forcing; constraining;
   resulting from, or enforced by, compulsion. [R.]
   [1913 Webster]

         To recover of us, by strong hand
         And terms compulsatory, those foresaid lands. --Shak.
   [1913 Webster]