Source : Webster's Revised Unabridged Dictionary (1913)

Armature \Ar"ma*ture\, n. (Elec.)
   That part of a dynamo or electric generator or of an electric
   motor in which a current is induced by a relatively moving
   magnetic field. The armature usually consists of a series of
   coils or groups of insulated conductors surrounding a core of
   iron.

Armature \Ar"ma*ture\, n. [L. armatura, fr. armare to arm: cf.
   F. armature. See {Arm}, v. t., {Armor}.]
   1. Armor; whatever is worn or used for the protection and
      defense of the body, esp. the protective outfit of some
      animals and plants.

   2. (Magnetism) A piece of soft iron used to connect the two
      poles of a magnet, or electro-magnet, in order to complete
      the circuit, or to receive and apply the magnetic force.
      In the ordinary horseshoe magnet, it serves to prevent the
      dissipation of the magnetic force.

   3. (Arch.) Iron bars or framing employed for the
      consolidation of a building, as in sustaining slender
      columns, holding up canopies, etc. --Oxf. Gloss.

Source : WordNet®

armature
     n : coil in which voltage is induced by motion through a
         magnetic field