A subterranean cavity or passage; especially:
(a)
A pit or excavation in the earth, from which metallic ores, precious stones, coal, or other mineral substances are taken by digging; distinguished from the pits from which stones for architectural purposes are taken, and which are called quarries.
(b)
(Mil.) A cavity or tunnel made under a fortification or other work, for the purpose of blowing up the superstructure with some explosive agent.