Nothing. It was just a cool, alliterative sounding way of referencing the day of the initial attack, when during the planning of the massive operation the actual day it would happen was not yet fixed. The landing in Normandy on June 6, 1944 was only one of dozens of "D-Day"s during the war - every allied amphibious assault had a D-Day, and there were many. Further, the attack began at "H-Hour", which again, meant nothing beyond the time when the attack would begin whenever D-Day was decided upon. D-Day for the Normandy landings was originally scheduled for early May, 1944, but was postponed for various reasons one month. Planning in terms of a D-Day allowed planners to project goals for the operation, to be reached by D+30 days, D+60 days, and D+90 days, and so on.
d
The D does not stand for anything. It is simply a D.
probably the first name
D stand for "Direct" or "Desk"
D - Deoxyribo N - Nucleic A - Acid
d for dad
It stands for whatever you choose it to stand for.
destruction
dagger
It stands for Domini.
David
The "D" stands for "Decongestant" .