To flatly refuse or spurn someone’s offer, request, or claim; to reject sharply.
彼は謝罪を受け入れず、相手の言葉をはねつけた。
He refused to accept the apology and brusquely rebuffed the other person’s words.
上司は追加予算の申請をあっさりとはねつけた。
The boss flatly rejected the request for additional budget.
彼女は助けを申し出た友人を丁寧に断らず、少し冷たくはねつけてしまった。
She ended up somewhat coldly spurning the friend who offered help, without a polite refusal.