Dictionary.com
Thesaurus.com
Synonyms

D-day

American  
[dee-dey] / ˈdiˌdeɪ /
Or D-Day

noun

  1. Military. the day, usually unspecified, set for the beginning of a planned attack.

  2. June 6, 1944, the day of the invasion of western Europe by Allied forces in World War II.

  3. Informal. any day of special significance, as one marking an important event or goal.


D-day British  

noun

  1. the day, June 6, 1944, on which the Allied invasion of Europe began

  2. the day on which any large-scale operation is planned to start

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

D-Day Cultural  
  1. The code name for the first day of a military attack, especially the American and British invasion of German-occupied France during World War II on June 6, 1944 (see invasion of Normandy). This marked the beginning of the victory of the Allies in Europe. Germany surrendered less than a year later.


Etymology

Origin of D-day

First recorded in 1918; D (for day ) + day; the same pattern as H-hour

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Veterans, officials and visitors commemorate D-day on the beaches of Normandy to honor those who fought for freedom in Europe in World War II.

From Los Angeles Times • Jun. 6, 2024

"Well guys, it's official. D-day has come and gone. It's gone past five o'clock, Monday. No contract has been signed," Fury said on Instagram.

From BBC • Sep. 26, 2022

James should have been part of the U.S. forces that invaded the beaches of Normandy, France, for D-day in June 1944.

From Los Angeles Times • Feb. 10, 2022

In late 2020, as Flash D-day drew near, supporters scrambled to rescue it.

From Slate • Feb. 5, 2021

Iwo Jima wasn’t just “softened up” for a few days before D-day.

From "Code Talker: A Novel About the Navajo Marines of World War Two" by Joseph Bruchac