15 letters: demographically, disillusionment, dispassionately, distastefulness, dissatisfaction
16 letters: disproportionate, depressurization, disagreeableness, declassification
17 letters: demonstrativeness, depersonalization, decriminalization
18 letters: disenfranchisement, distinguishability
How about "disestablishmentarianism"? It means the concept of separation of church and state. It's the root of the much more popular word "antidisestablishmentarianism" which a lot of people like to rattle off as a token "big word" they know.
Though, you're probably looking for something more practical. To be honest, there are thousands of big words that start with D. My advice would be browsing a dictionary under D until something big hits your eye. A lot of them involve simply adding "dis-" or "de-" onto longer concepts.
drawn out The ceremony could have been brief, but instead it was long and drawn out.
words that start with any
Any word on Earth that starts with D.
dumorge
Compound words beginning with D:darkroomdashboarddaybeddaybreakdaydreamdaylightdaytimedeadbeatdeadboltdeadlinedeathwatchdewdropdinnertimedirtballdishclothdishpandishwasherdoorbelldoorstepdownplaydownspoutdowntimedragnetdriftwooddrugstoredrywalldumbbell
Dont you think that is a stupid fact? Starts with "D". Is it? Starts with "I". Could it be? starts with "C". Does it? starts with "D". Anyone agree? Starts with "A".
Darling and delicious are happy words. They begin with D.
Dashing, debonair
There are many words starting with the letter d in history, here are three examples. Doomsday Book. D-Day. Dambusters.
One word that starts with d and ends with w is DEW.
Some five letter words that start with D are:dailydairydaisydandydeathdebutdecordeferdemurdepthdiaryDreamdummydutch
Domain is one of the words that starts with the letter D and ends with the letter N.
· afford · applaud · attend · avoid