[1] : The Collaborative International Dictionary of English v.0.48

d-day \d-day\ n.
   1. mil. the day designated for the beginning of a planned
      attack by a military force; in communications the day is
      often otherwise unspecified for security reasons; as, the
      day before d-day the troops will move into position.
      pjc

   2. 6 june 1944, the day of the landing in france, by troops
      allied against the germans in world war ii.

   syn: 6 june 1944.
        wordnet 1.5

   3. the day for commencement or execution of any elaborate
      planned activity; -- often used jocosely. informal
      pjc

[2] : WordNet (r) 2.0

d-day
     n : day of the allied landing in france, world war ii syn: 6
         june 1944
see also:
6 june 1944 

Dday >> D Words
Dday, definition of term: Dday
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