:a day on which something important is planned or expected to happen重大事件预定发生日;计划行动开始日
The day after Thanksgiving is D-day for many retail stores.感恩节过后是许多零售商店销售旺季的开始。
◊ D-day is most commonly used to refer to the specific date of June 6, 1944, when Allied forces began the invasion of France in World War II.第二次世界大战中盟军登陆诺曼底的日子(即1944年6月6日)