equipotential surface

from The Collaborative International Dictionary of English v.0.48

Equipotential \E`qui*po*ten"tial\, a. [Equi- + potential.]
   (Mech. & Physics)
   Having the same potential.
   [1913 Webster]

   {Equipotential surface}, a surface for which the potential is
      for all points of the surface constant. Level surfaces on
      the earth are equipotential.
      [1913 Webster]