オつ

おつ · otsu

verb 終止形

To fall, to drop, to come down, to crash, to collapse, to cave in, to give way

to set (of the sun or moon), to sink, to dip, to go down
to decrease (of popularity, quality, speed, sales, etc.), to fall, to drop, to go down, to decline, to deteriora

Classical Japanese — you’ll mostly meet it in older texts and set phrases

Full entry for おっ

In real sentences

先生は毎日、基礎練習を欠かさないようにとおっしゃった。

せんせいはまいにち、きそれんしゅうをかかさないようにとおっしゃった。

The teacher said to never skip basic practice every day.

Nihoner sentence bank