A roughly horizontal passage introduced into a mine for the purpose of access or drainage. Also in extended use; spec. a watercourse, esp. one that…

(a) the upper portion of the bank of a river, lake, etc.; (b) Mining the mouth of a pit or quarry (cf. sense 12).

The surface opening of a pit, cave, well, ditch, etc.; (figurative) the entrance to Hell.

Mining. As a mass noun. The area surrounding the top of a shaft or the mouth of a pit. Chiefly in to (also at) bank.

A subterranean drain to carry off the water in a mine; an adit of a mine.

The top of a mine shaft; the area or buildings immediately surrounding this.

in Mining.

The entrance to an underground working from a mine shaft.