Definition of D-Day noun from the Oxford Advanced American Dictionary

 

D-Day

 noun
noun
NAmE//ˈdi deɪ//
 
[uncountable]
 
jump to other results
a date on which something important is expected to happen From the name given to June 6, 1944, the day on which the U.S., British, and other armies landed on the beaches of northern France in the Second World War.
See the Oxford Advanced Learner's Dictionary entry: D-Day