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Webster 1913 Edition
Grindstone
Grind′stoneˊ
,Noun.
A flat, circular stone, revolving on an axle, for grinding or sharpening tools, or shaping or smoothing objects.
They might be ashamed, for lack of courage, to suffer the Lacedæmonians to
hold their noses to the grindstone
. Sir T. North.
Webster 1828 Edition
Grindstone
GRIND'STONE
,Noun.
Stone, used by old writers, is obsolete.