The settlement or conclusion of a dispute or problem; the point at which a matter is decided or resolved.
あの件は話し合いで決着がついた。
That matter was settled by discussion.
勝敗に関しては最後まで決着がつかなかった。
The outcome in terms of victory or defeat wasn't decided until the end.
問題を先送りにせず、早く決着をつけよう。
Let's not postpone the issue and settle it quickly.