noun
cancelling a debt; forgiving a debt; being even
Colloquial term for wiping the slate clean financially, often used in phrases like チャラにする (to call it even).
この前貸した金はチャラにしてやるよ。
I'll forget about the money I lent you the other day.
おごってもらったから、これでチャラね。
You treated me, so we're even now.
noun
forgetting what was said or done; pretending something never happened
Colloquial extension: treating a past remark or incident as if it never happened, often in the phrase チャラにする.
さっきの失言はチャラにしてくれ。
Forget what I just said—pretend it never happened.
喧嘩のことはもうチャラにしよう。
Let's just forget about the fight.
The exact origin is uncertain. It may be related to the onomatopoeic sound of something being erased or wiped away, or possibly derived from a contraction of ちゃらんぽらん (irresponsible).