To come to a conclusion or be settled (e.g., a dispute); to reach a decisive outcome.
交渉が長引いたが、ようやく決着がついた。
Negotiations dragged on, but they finally came to a conclusion.
勝敗に決着がつくまで試合は続行される。
The match continues until a winner is decided.
彼らの争いにはまだ決着がついていない。
Their dispute has not yet been settled.
この証拠で事件の真相に決着がつくだろう。
This evidence will probably settle the truth of the case.