with no hard feelings; no grudges
Used when agreeing to let go of resentment, often after a competition or dispute. Common in phrases like 恨みっこなしだよ or 恨みっこなしにしよう.
A match is a match; no hard feelings.
We're even, so let's not hold any grudges.
Alternate spelling using the kanji 無し for なし.
From 恨み (grudge) + っこ (suffix indicating mutual action) + なし (without). The っこ element adds a nuance of reciprocity.