goaf

Century Dictionary and Cyclopedia

1. n. A stack or cock, as of grain.
2. n. A rick of corn in the straw laid up in a barn.
3. n. 3. In coal-mining, a space from which coal has been worked away, and which is more or less filled up with refuse. In this sense generally used in the plural, the goaves. The refuse rock or material with which the goaves are filled is called gob, or sometimes goaf. It is the attle or deads of the metal-miner. See gob.

Wiktionary

1. n. mining That part of a mine from which the mineral has been partially or wholly removed; the waste left in old workings.

GNU Webster's 1913

1. n. (Mining) That part of a mine from which the mineral has been partially or wholly removed; the waste left in old workings; -- called also gob .