Definition of pit

i. Depression produced in a metal surface by nonuniform electrodeposition or by corrsion.

Ref: Lowenheim

ii. Excavation to hold quantities of water and drilling fluids.

Ref: Wheeler, R.R.

iii. So. Wales. Long, open-air fire for converting coal into coke for blast-furnace purposes.

Ref: Fay


iv. A mine, quarry, or excavation worked by the open-cut method to obtain material of value.

Ref.:
https://en.wikipedia.org/wiki/Open-pit_mining


v. The shaft of a mine; a shaft mine; a trial pit.

Ref: Nelson

vi. The underground portion of a colliery, including all workings. Used in many combinations, as pit car, pit clothes, etc.

vii. In hydraulic mining, the excavation in which piping is carried forward.

viii. Commonly, a coal mine, but not usually called so by workers, except in reference to surface mining where the workings may be known as a strip pit.

Ref: BCI

ix. See: abyss