v.tr.
1. injure (a person, reputation, influence, etc.) by secret or insidious means.
2 weaken, injure, or wear out (health etc.) imperceptibly or insidiously.
3 wear away the base or foundation of (rivers undermine their banks).
4 make a mine or excavation under.
Derivatives:
underminer n. underminingly adv.
Etymology: ME f. UNDER- + MINE(2)