Source : Webster's Revised Unabridged Dictionary (1913)

Coach \Coach\, v. t. [imp. & p. p. {Coached}; p. pr. & vb. n.
   {Coaching}.]
   1. To convey in a coach. --Pope.

   2. To prepare for public examination by private instruction;
      to train by special instruction. [Colloq.]

            I coached him before he got his scholarship. --G.
                                                  Eliot.