1) A disc of stone of considerable thickness which revolves on an iron axle and is used for grinding, sharpening or polishing (OED).
1437 ‘a quarry of grynstanes’, Bowes
1464-5 60 grynstones, Hull
1510 of ylka gryndestonne, York
1541 my gryndinge stones … in Ledes, Skipton, Kighley and Heptonstall
1543 2 grynstons unge in yron, Ripley
1578-9 ‘two stones called grynding stones’, Ecclesfield
1622 2 grundill stones, 3 stone troughes, Cottingley. The cutlers’ grindstones were mostly water-powered, and the quality of the stone available in the Sheffield area is seen as one of the major reasons for the success there of the cutlery trade. In 1637, John Harrison considered the course grinding stones for knives and scithes to be a major local resource and they were probably in use by up to 500 master workmen by that time. The alternative word, grindlestone, is recorded from the thirteenth century, notably in the alliterative poem Sir Gawain and the Green Knight: As one vpon a gryndelston hade grounden a syţe. It was common in Yorkshire from the sixteenth century: 1534 a stone troughe, a gryndle ston, Liversedge
1583 for a gryndle-stone 2s 4d, York
1639 Item grinelstones, Swinsty. The places where grindstones were quarried or stored are commemorated in some minor place-names, e.g. Grindstone Hill, Grinding Stone Hole, Grinnel Stones
the cliffs at Whitby: 1544-5 lapidum vocatam gryndelstones in lez cliffes. The place-name Grindlestone Bank is on record in Ovenden from 1536.