This is the 19124th most frequent Korean word.
아차
"아차" means "Oops" or an exclamation used when realizing a mistake or oversight.
In this instance, '아차' expresses sudden realization or recognition of a mistake.
아차, 내가 문을 잠그는 것을 잊었어.
Oh no, I forgot to lock the door.
Here, '아차' conveys a sense of realizing a responsibility or oversight on oneself.
아차, 이건 내가 맡은 책임이야.
Oops, this is my responsibility.
In this case, '아차' is used to indicate the acknowledgment of misunderstanding an information.