The Collaborative International Dictionary of English v.0.48:

Empoison \Em*poi"son\, v. t. [F. empoisonner; pref. em- + F.
   poison. See Poison, and cf. Impoison.]
   To poison; to impoison. --Shak.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Empoison \Em*poi"son\, n.
   Poison. [Obs.] --Remedy of Love.
   [1913 Webster]