1) Countermeasure 2) To plot opposition 3) To sap hostile mining 1) Derail 2) Undermine 
• (n.) An underground gallery excavated to intercept and destroy the mining of an enemy. • (v. t.) To oppose by means of a countermine; to intercept with a countermine. • (v. i.) To make a countermine or counterplot; to plot secretly. • (v. t.) To frustrate or counteract by secret measures. • (n.) A stratagem or plot by whi...
Coun'ter·mine` (koun'tẽr*mīn`) noun [ Counter- + mine underground gallery: confer French contermine .] 1. (Mil.) An underground gallery excavated to intercept and destroy the mining of an enemy. 2. A stratagem or plot by which another sratagem...Coun`ter·mine' (koun`tẽr*mīn') transitive verb [ Confer French contreminer .] [ imperfect & past participle Countermined ; present participle & verbal noun Countermining .] 1. (Mil.) To oppose by means...Coun`ter·mine' intransitive verb To make a countermine or counterplot; to plot secretly. « 'Tis hard for man to countermine with God. Chapman. » 
[n] - (military) a tunnel dug to defeat similar activities by the enemy 2. [v] - destroy enemy mines with one`s own mines
noun (military) a tunnel dug to defeat similar activities by the enemy