whetstone; grindstone; sharpening stone
A stone used for sharpening blades such as knives, chisels, or swords. Both natural and synthetic stones are called 砥石.
I sharpen the kitchen knife on a whetstone.
この砥石は目の粗さが違う面がある。
This whetstone has sides with different grits.
grindstone; round whetstone
oilstone
Standard kanji spelling for a sharpening stone.
Kana spelling is sometimes used in everyday contexts, especially when the kanji 砥 is less familiar.
Compound of 砥 “whetstone” and 石 “stone.” The reading joins と and いし without voicing.