A daughter was part of a group trivia contest where the answer for the meaning of the D in D-day was just "day". This was said to be similar to the h in h-hour also just being "hour" again.
I grew up having read that the D meant disembarkation. I found this short article on some other meanings people have attributed to the D. (The 75 anniversary of the D-Day that most people think of when they hear the term is coming up this Thursday. But there were many D-days during WWII.)
In Paul Dickson’s War Slang, he quotes Robert Hendrickson’s Encyclopedia of Word and Phrase Origins, Many explanations have been given for the meaning of D-Day, June 6, 1944, the day the Allies invaded Normandy from England during World War II. The Army has said that it is “simply an alliteration, as in H-Hour.” Others say the first D in the word also stands for “day,” the term a code designation. The French maintain the D means “disembarkation,” still others say “debarkation,” and the more poetic insist D-Day is short for “day of decision.” When someone wrote to General Eisenhower in 1964 asking for an explanation, his executive assistant Brigadier General Robert Schultz answered: “General Eisenhower asked me to respond to your letter. Be advised that any amphibious operation has a ‘departed date’; therefore the shortened term ‘D-Day’ is used.”
https://www.army.mil/e2/downloads/rv7/d-day/the-meaning-of-dday-fact.pdf
I grew up having read that the D meant disembarkation. I found this short article on some other meanings people have attributed to the D. (The 75 anniversary of the D-Day that most people think of when they hear the term is coming up this Thursday. But there were many D-days during WWII.)
In Paul Dickson’s War Slang, he quotes Robert Hendrickson’s Encyclopedia of Word and Phrase Origins, Many explanations have been given for the meaning of D-Day, June 6, 1944, the day the Allies invaded Normandy from England during World War II. The Army has said that it is “simply an alliteration, as in H-Hour.” Others say the first D in the word also stands for “day,” the term a code designation. The French maintain the D means “disembarkation,” still others say “debarkation,” and the more poetic insist D-Day is short for “day of decision.” When someone wrote to General Eisenhower in 1964 asking for an explanation, his executive assistant Brigadier General Robert Schultz answered: “General Eisenhower asked me to respond to your letter. Be advised that any amphibious operation has a ‘departed date’; therefore the shortened term ‘D-Day’ is used.”
https://www.army.mil/e2/downloads/rv7/d-day/the-meaning-of-dday-fact.pdf
