UNDERMI'NE, verb transitive

1. To sap; to excavate the earth beneath, for the purpose of suffering to fall, or of blowing up; as, to undermine a wall.

2. To excavate the earth beneath. Rapid streams often undermine their banks and the trees growing upon them.

3. To remove the foundation or support of any thing by clandestine means; as, to undermine reputation; to undermine the constitution of the state.

He should be warned who are like to undermine him.