The Collaborative International Dictionary of English v.0.48:

Accouplement \Ac*cou"ple*ment\ (-k[u^]p"'l*ment), n. [Cf. F.
   accouplement.]
   1. The act of coupling, or the state of being coupled; union.
      [R.] --Caxton.
      [1913 Webster]

   2. That which couples, as a tie or brace. [R.]
      [1913 Webster]