Source : Webster's Revised Unabridged Dictionary (1913)

Undermine \Un`der*mine"\, v. t.
   1. To excavate the earth beneath, or the part of, especially
      for the purpose of causing to fall or be overthrown; to
      form a mine under; to sap; as, to undermine a wall.

            A vast rock undermined from one end to the other,
            and a highway running through it.     --Addison.

   2. Fig.: To remove the foundation or support of by
      clandestine means; to ruin in an underhand way; as, to
      undermine reputation; to undermine the constitution of the
      state.

            He should be warned who are like to undermine him.
                                                  --Locke.

Source : WordNet®

undermine
     v 1: destroy property or hinder normal operations; "The
          Resistance sabotaged railroad operations during the war"
          [syn: {sabotage}, {countermine}, {counteract}, {subvert},
           {weaken}]
     2: hollow out as if making a cave or opening; "The river was
        caving the banks" [syn: {cave}]