Source : Webster's Revised Unabridged Dictionary (1913)

Pitch \Pitch\, n. (Elec.)
   The distance between symmetrically arranged or corresponding
   parts of an armature, measured along a line, called the pitch
   line, drawn around its length. Sometimes half of this
   distance is called the pitch.

   {Pitch of poles} (Elec.), the distance between a pair of
      poles of opposite sign.