1918, "date set for the beginning of a military operation," with D as an abbreviation of day; compare H-hour, also from the same military order of Sept. 7, 1918:
The First Army will attack at H-Hour on D-Day with the object of forcing the evacuation of the St. Mihiel salient. [Field Order No. 8, First Army, A.E.F.]
"They designate the day and hour of the operation when the day and hour have not yet been determined, or where secrecy is essential" [U.S. Army Center of Military History Web site]. Now almost exclusively of June 6, 1944.
双语例句
1. Butter, margarine, and oily fish are all good sources of vitamin D.
黄油、人造黄油和多脂鱼都含有丰富的维生素D。
来自柯林斯例句
2. In figure 24 "D" denotes quantity demanded and "S" denotes quantity supplied.
在图24中，D代表需求量而S代表供应量。
来自柯林斯例句
3. Milk, oily fish and egg all contain vitamin D.
牛奶、油性鱼类和鸡蛋都含有维生素D.
来自柯林斯例句
4. This special form of vitamin D is naturally present in breast milk.
