undermineˈ (Spenser undermindeˈ) transitive verb

1. To dig beneath (eg a wall) in order to make it fall
2. To wash away or remove by burrowing, etc, the ground from under
3. To weaken gradually or insidiously
4. To intrigue against
5. To tamper with the fidelity of

undermīˈner noun

undermīˈning noun