1. (v. t.) To excavate the earth beneath; to subvert by indirect, secret, or underhanded means\; to form a mine under; to sap; as, to undermine a wall.

2. (v. t.) 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.

abate answer answer conclusively argue down attenuate blunt bugger up confound confute contradict controvert cramp cripple crush damage damp dampen dash deaden debilitate defeat demolish deny devitalize disable dismiss dispose of drain dull enervate enfeeble eviscerate exhaust extenuate finish floor foil frustrate gruel harm honeycomb hurt impair lay low mine mitigate nonplus overset overthrow overturn overwhelm parry put to silence queer rattle rebut reduce reduce to silence refute ruin sabotage sap sap the foundations settle shake shake up shut up silence smash all opposition soften up spoil squash squelch subvert threaten throw down throw over thwart unbrace undercut unman unnerve unstrengthen unstring upend upset weaken wreck