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Webster 1913 Edition
Goaf
Goaf
;Noun.
pl.
Goafs
(#)
or Goaves
(#)
. [Cf. 1st
Gob
.] (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
. To work the goaf
or To work the gob
to remove the pillars of mineral matter previously left to support the roof, and replace them with props.
Ure.