coal-mine (also pit)

n place underground where coal is dug 煤矿.

co-ordinator, co-pilot, copilot, co-religionist, coreligionist, co-respondent, corespondent, co-signatory, cosignatory, co-star, co-tenant, coach, coachman, coachwork, coagulant, coagulate, coagulation, coal, coal gas, coal oil, coal tar, coal-black, coal-face (also face), coal-hole, coal-miner, coal-scuttle (also scuttle), coal-seam, coalesce, coalescence, coalfield, coalition, coaming, coarse, coarse fish, coarse fishing, coarsely, coarsen, coarseness, coast, coastal, coaster, coastguard, coastline, coat,