D-day Definition

dēdā
noun
The unnamed day on which an operation or offensive is to be launched.
American Heritage
The day on which a military attack or other important event is to take place; specif., June 6, 1944, the day of the invasion of W Europe by Allied forces in WWII.
Webster's New World

(figuratively) The date of any major event planned for the future.

Wiktionary
Synonyms:
  • 6 June 1944

Other Word Forms of D-day

Noun

Singular:
D-day
Plural:
d-days

Origin of D-day

  • D (abbr. of day) day

    From American Heritage Dictionary of the English Language, 5th Edition

Words Near D-day in the Dictionary