from The American Heritage® Dictionary of the English Language, 4th Edition
- transitive v. To weaken by wearing away a base or foundation: Water has undermined the stone foundations.
- transitive v. To weaken, injure, or impair, often by degrees or imperceptibly; sap: Late hours can undermine one's health.
- transitive v. To dig a mine or tunnel beneath.
from the GNU version of the Collaborative International Dictionary of English
- transitive v. 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.
- transitive v. Fig.: To remove the foundation or support of by clandestine means; to ruin in an underhand way.
from The Century Dictionary and Cyclopedia
- To form a mine under; sap; render unstable by digging or wearing away the foundation of; make an excavation beneath, especially for the purpose of causing to fall, or of blowing up: as, to undermine a wall; a river undermines its banks.
- Figuratively, to subvert by removing clandestinely the foundation of; injure by invisible, secret, or dishonorable means.
- To injure, weaken, or destroy insidiously or indirectly; wear away; wear out; sap.
- n. Same as mine, 2 .
- n. A cave.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- v. destroy property or hinder normal operations
- v. hollow out as if making a cave or opening
From under- + mine. (Wiktionary)