The Other Day, A Few Days Ago, Other Day
noun
The previous day isn't necessarily yesterday. It can be any recent day, which is why this word means the other day.
せんじつ
This is a jukugo word, which usually means on'yomi readings from the kanji. Since 日 has two on'yomi readings, here's a mnemonic to help you remember which one to use: The other day, you saw two centaurs! Gee, two (せんじつ) of them?! You're lucky you're still alive!
先日はどうもありがとうございました。
Thank you so much for the other day.
先日のパーティー、中止でしたね。
The party the other day got canceled.
先日のアイディアは気に入っていただけましたか？
Did you like my idea from the other day?