[1] : The Collaborative International Dictionary of English v.0.48

goaf \goaf\; n.; pl. goafsor 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 .
   1913 webster

   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.
      1913 webster
see also:
goafs goaves gob gob to work the goaf to work the gob 

Gob >> G Words
Gob, definition of term: Gob
gob_pag1.html

At Work >> A Words
At Work, definition of term: At Work
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gob in TutorGig Dictionary
...... To work the goaf or To work the gob, to remove the pillars of mineral ... Gob * Gob Fans * Atlyrics.com - Gob * Gob Heaven * Mark''s Gob Page ... ..
http://www.tutorgig.com/d/gob, score=100, date indexed=November 11, 2005, 5:08 am

Gob in TutorGig Dictionary
...... To work the goaf or To work the gob, to remove the pillars of mineral ... Gob * Gob Fans * Atlyrics.com - Gob * Gob Heaven * Mark''s Gob Page ... ..
http://www.tutorgig.com/d/Gob, score=100, date indexed=November 6, 2005, 5:48 pm

gob | TutorGig.co.uk Dictionary
...... To work the goaf or To work the gob, to remove the pillars of mineral ... Gob * Gob Fans * Atlyrics.com - Gob * Gob Heaven * Mark''s Gob Page ... ..
http://www.tutorgig.co.uk/dict.jsp?keywords=gob, score=51, date indexed=December 16, 2005, 12:20 pm

goaf | TutorGig.co.uk Dictionary
...... To work the goaf or To work the gob, to remove the pillars of mineral ... 1st Gob.] (Mining) That part of a mine from which the mineral has been ... ..
http://www.tutorgig.co.uk/dict.jsp?keywords=goaf, score=49, date indexed=December 9, 2005, 4:26 am

Goaf
...To work the goaf} or {To work the gob}, to remove the pillars of ... 1st Gob.] (Mining) That part of a mine from which the mineral has been ... ..
http://goaf.idoneos.com/, score=49, date indexed=January 1, 2006, 2:46 am

To walk the plank to Tod stove : Definition from the Online Dictionary at ...
...... To work into To work off To work out To work the goaf To work the gob ... To-beat To-break To-brest To-day To-do To-fall To-name To-rend To-rent ... ..
http://onlinedictionary.datasegment.com/wordlist/T56, score=48, date indexed=December 9, 2005, 8:17 am