noun
stone mortar; millstone; quern
A traditional stone grinding tool used for milling grains, beans, or other materials. The term covers both the stationary base and the rotating upper stone.
祖母は石臼で大豆を挽いてきな粉を作った。
My grandmother ground soybeans with a stone mortar to make kinako.
この石臼は江戸時代から使われている。
This stone mortar has been used since the Edo period.
Compound of 石 (ishi, 'stone') and 臼 (usu, 'mortar'). The reading いしうす is a straightforward combination of the two elements.