1A firm resolve or determination to do something; the act of making up one's mind.
彼は会社を辞めて留学することを決心した。
He made up his mind to quit his job and study abroad.
何度も失敗したが、諦めない決心は変わらなかった。
I failed many times, but my resolve not to give up never wavered.
手術を受けるかどうか、彼女はまだ決心がつかないようだ。
She still doesn't seem to have made up her mind about whether to undergo the surgery.