Source : Webster's Revised Unabridged Dictionary (1913)

Untrained \Un*trained"\, a.
   1. Not trained. --Shak.

   2. Not trainable; indocile. [Obs.] --Herbert.

Source : WordNet®

untrained
     adj : not disciplined or conditioned or made adept by training;
           "an untrained voice"; "untrained troops"; "young minds
           untrained in the habit of concentration" [ant: {trained}]