Source : Webster's Revised Unabridged Dictionary (1913)

Transformer \Trans*form"er\, n.

   {Multiple transformer}. (Elec.)
   (a) A transformer connected in multiple or in parallel with
       the primary circuit.
   (b) A transformer with more than one primary or more than one
       secondary coil.

   {Parallel transformer} (Elec.), a transformer connected in
      parallel.

Transformer \Trans*form"er\, n.
   One who, or that which, transforms. Specif. (Elec.), an
   apparatus for producing from a given electrical current
   another current of different voltage.

Source : WordNet®

transformer
     n : an electrical device by which alternating current of one
         voltage is changed to another voltage