Source : Webster's Revised Unabridged Dictionary (1913)

Coach \Coach\, v. i.
   To drive or to ride in a coach; -- sometimes used with it.
   [Colloq.] ``Coaching it to all quarters.'' --E. Waterhouse.

Coach \Coach\ (?; 224), n. [F. coche, fr. It. cocchio, dim. of
   cocca little boat, fr. L. concha mussel, mussel shell, Gr. ?,
   akin to Skr. [,c]ankha. Cf. {Conch}, {Cockboat}, {Cockle}.]
   1. A large, closed, four-wheeled carriage, having doors in
      the sides, and generally a front and back seat inside,
      each for two persons, and an elevated outside seat in
      front for the driver.

   Note: Coaches have a variety of forms, and differ in respect
         to the number of persons they can carry. Mail coaches
         and tallyho coaches often have three or more seats
         inside, each for two or three persons, and seats
         outside, sometimes for twelve or more.

   2. A special tutor who assists in preparing a student for
      examination; a trainer; esp. one who trains a boat's crew
      for a race. [Colloq.]

            Wareham was studying for India with a Wancester
            coach.                                --G. Eliot.

   3. (Naut.) A cabin on the after part of the quarter-deck,
      usually occupied by the captain. [Written also {couch}.]
      [Obs.]

            The commanders came on board and the council sat in
            the coach.                            --Pepys.

   4. (Railroad) A first-class passenger car, as distinguished
      from a drawing-room car, sleeping car, etc. It is
      sometimes loosely applied to any passenger car.

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.

Source : WordNet®

coach
     n 1: (sports) someone in charge of training an athlete or a team
          [syn: {manager}, {handler}]
     2: a person who gives private instruction (as in singing or
        acting) [syn: {private instructor}, {tutor}]
     3: a railcar where passengers ride [syn: {passenger car}, {carriage}]
     4: a carriage pulled by four horses with one driver [syn: {four-in-hand},
         {coach-and-four}]
     5: a vehicle carrying many passengers; used for public
        transport; "he always rode the bus to work" [syn: {bus}, {autobus},
         {charabanc}, {double-decker}, {jitney}, {motorbus}, {motorcoach},
         {omnibus}]

coach
     v 1: teach and supervise (someone); act as a trainer or coach
          (to), as in sports; "He is training our Olympic team";
          "She is coaching the crew" [syn: {train}]
     2: drive a coach