In mining law. A lateral entrance or passage into a mine; the opening by which a mine is entered or by which water and ores are carried away; a horizontal excavation in and along a lode. ElectroMagnetic M. & D. Co. v. Van Auken, 9 Colo. 204, 11 Pac. 80; Gray v. Truby, 6 Co.lo. 278.