An expression of approval, agreement, or that something is fine—used to say 'okay' or 'all right'.
明日10時でＯＫ？
Is 10 o'clock tomorrow OK?
その案は上司がＯＫを出した。
The boss approved that plan.
撮影の準備は全部ＯＫです。
Everything is ready for filming.
問題がなければ、このまま進めてＯＫです。
If there are no problems, it's OK to proceed as is.
Used to indicate that something is not necessary or that it is fine to do without (e.g., 'it's OK not to ...').
この書類は当日持ってこなくてもＯＫです。
You don't have to bring this document on the day; it's OK.
傘は持ってこなくてＯＫ。会場で貸し出しがあります。
You don't need to bring an umbrella; there are rentals at the venue.
細かい点は気にしなくてＯＫだよ。
You don't need to worry about the small details.