Source : Webster's Revised Unabridged Dictionary (1913)

Trainer \Train"er\, n.
   1. One who trains; an instructor; especially, one who trains
      or prepares men, horses, etc., for exercises requiring
      physical agility and strength.

   2. A militiaman when called out for exercise or discipline.
      [U. S.] --Bartlett.

Source : WordNet®

trainer
     n 1: one who trains other persons or animals
     2: simulator consisting of a machine on the ground that
        simulates the conditions of flying a plane [syn: {flight
        simulator}]