tea grinding mortar; hand mill for tea
A traditional stone or ceramic hand mill used to grind tea leaves into matcha powder. Often associated with tea ceremony contexts.
Grinding matcha with a tea mortar takes time.
Compound of 茶 (tea) and 臼 (mortar). The reading ちゃうす is a straightforward combination of the on'yomi of 茶 and the kun'yomi of 臼.