Webster's Revised Unabridged Dictionary · 1913

Whetstone

Whetstone , noun

[Anglo-Saxon hwetstān.]

A piece of stone, natural or artificial, used for whetting, or sharpening, edge tools.
The dullness of the fools is the whetstone of the wits. — Shakespeare
Diligence is to the understanding as the whetstone to the razor. — South

Some whetstones are used dry, others are moistened with water, or lubricated with oil.

Collocations (1)
To give the whetstone , to give a premium for extravagance in falsehood. [Obsolete]