vt to frustrate or counteract by secret measures.
2. countermine ·vi to make a countermine or counterplot; to plot secretly.
3. countermine ·noun a stratagem or plot by which another sratagem or project is defeated.
4. countermine ·vt to oppose by means of a countermine; to intercept with a countermine.
5. countermine ·noun an underground gallery excavated to intercept and destroy the mining of an enemy.