(1):

(v. i.) To make a countermine or counterplot; to plot secretly.

(2):

(n.) An underground gallery excavated to intercept and destroy the mining of an enemy.

(3):

(v. t.) To frustrate or counteract by secret measures.

(4):

(v. t.) To oppose by means of a countermine; to intercept with a countermine.

(5):

(n.) A stratagem or plot by which another sratagem or project is defeated.