Very quick; rapid; prompt — acting swiftly and appropriately.
迅速な対応のおかげで被害が最小限にとどまった。
Thanks to the prompt response, the damage was kept to a minimum.
彼は問題発覚後、迅速に報告書を作成した。
He quickly prepared a report after the problem was discovered.
迅速に処理してください。
Please handle this promptly.