Noah Webster's Dictionary 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.

Multi-Version Concordance Undermine (1 Occurrence) 2 Corinthians 11:12 and what I do, I also will do, that I may cut off the occasion of those wishing an occasion, that in that which they boast they may be found according as we also; (See RSV)