Source : Webster's Revised Unabridged Dictionary (1913)

Equipotential \E`qui*po*ten"tial\, a. [Equi- + potential.]
   (Mech. & Physics)
   Having the same potential.

   {Equipotential surface}, a surface for which the potential is
      for all points of the surface constant. Level surfaces on
      the earth are equipotential.