n. 磨石

[ noun ]
a flat stone for sharpening edged tools or knives
<noun.artifact>

Whetstone \Whet"stone`\, n. [AS. hwetst[=a]n.]
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.
--Shak.

Diligence is to the understanding as the whetstone to
the razor. --South.

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

{To give the whetstone}, to give a premium for extravagance
in falsehood. [Obs.]