The Collaborative International Dictionary of English v.0.48:

Premonish \Pre*mon"ish\, v. t. [imp. & p. p. Premonished; p.
   pr. & vb. n. Premonishing.] [Pref. pre- + monish: cf. L.
   praemonere.]
   To forewarn; to admonish beforehand. [R.] --Herrick.
   [1913 Webster]

         To teach, and to premonish.              --Bk. of Com.
                                                  Prayer.
   [1913 Webster]