noun
18-litre measuring container
A traditional square wooden box used for measuring rice or other grains, equivalent to one to (about 18 litres). Often seen in historical or cultural contexts.
昔は一斗枡でお米を量っていた。
In the old days, they measured rice with an 18-litre measuring container.
Compound of 一斗 (itto, 'one to', a unit of volume) and 枡 (masu, 'measuring box'). The exact historical derivation is uncertain, but the term directly describes its function.