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• D-day
  D-day

  noun

  the day, usually unspecified, set for the beginning of a planned attack.
• D-Day
  D-Day

  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.

D-day

American  

[dee-day] / 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.

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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

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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.

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Etymology

Origin of D-day

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

Example Sentences

See Examples For:

D-day D-Day

“Pressure,” the new World War II movie from director Anthony Maras and writer David Haig, is a hyperfocused look at the days leading up to D-day with a special focus on the weather.

From Los Angeles Times ● May 29, 2026

In the film, Scott’s Stagg arrives at Southwark House from Dunstable four days before D-day is planned.

From Los Angeles Times ● May 29, 2026

“He wrote two letters on the eve of D-day: what happens in success and what happens in failure,” Maras says.

From Los Angeles Times ● May 29, 2026

After Stagg convinces the leaders to postpone D-day, he is vindicated by a deluge of rain that arrives while everyone is attending church at Southwark House on June 5.

From Los Angeles Times ● May 29, 2026

Then, in August 2009, the city decided to pardon the children who had participated in the 1963 D-day and Double D-day protest.

From "While the World Watched: A Birmingham Bombing Survivor Comes of Age during the Civil Rights Movement" by Carolyn Maull McKinstry

Two months after D-Day, in August 1944, Peter Ortiz led an ambush against Nazi forces in the French Alps.

From The Wall Street Journal ● Oct. 5, 2026

Normandy veteran Kenneth Hay, who survived being captured just weeks after D-Day and spent years educating children about World War Two, has died aged 101.

From BBC ● Sep. 21, 2026

When we commemorate the D-Day victory at Normandy, we don’t discuss why American planners failed to anticipate the dangers of the hedgerows beyond the beaches, where many American servicemen subsequently died.

From The Wall Street Journal ● Sep. 11, 2026

Bessent dubbed the initiative Economic D-Day, likening the effort to the World War II campaign.

From The Wall Street Journal ● Aug. 25, 2026

By July 10, 1944, one month after the D-Day invasion, the Allies controlled most of Normandy.

From "Hitler Youth: Growing Up in Hitler's Shadow" by Susan Campbell Bartoletti