definition of
countermine

[1] #1 countermine n. (military) a tunnel dug to defeat similar activities by the enemy. wn

[2] #2 countermine v. [sabotage, undermine, counteract, subvert, weaken] destroy property or hinder normal operations; "The Resistance sabotaged railroad operations during the war". wn

[3] #3 countermine v. destroy enemy mines with one's own mines; "We countermined the banks of the river". wn