The phrase "lengthy dinner" is correct and can be used in written English.
It is typically used when describing a dinner or meal that lasts for a long period of time. Example: After a lengthy dinner with his family, John felt satisfied and content as they shared stories and caught up on each other's lives.
The casual drink became a lengthy dinner.
Mr. Panetta had been traveling for 24 hours and had just come from a lengthy dinner with Mr. Karzai.
He told me that he had one lengthy dinner with Mr. Rezko and came to an instant conclusion.
Japanese Classic The quintessential meal of Japan is kaiseki, a lengthy dinner in which each of the many courses has its own artful presentation.
"There is a chatter and a high level of chatter both regionally and in other international spots," Prince Bandar bin Sultan, the Saudi ambassador to Washington, said at a lengthy dinner for a group of reporters convened in a sprawling woolen bedouin tent on the grounds of his residence here.
"We had a lengthy dinner in the middle of January, five hours of discussions that flowed naturally and even though we come from different sports worlds.
It is the tale of the complex negotiations, blinding flashes of insight, and lengthy dinners at exclusive Manhattan hotels which created the colossus that is Viacom.
After a lengthy, boozy dinner, Mr. Icahn made an offer: he would put $10 million in one of Mr. Ackman's favorite charities to settle the dispute once and for all.
Mr Obama discussed the deepening crisis in Syria with other G20 delegates at a lengthy working dinner on Thursday night - and it was there, correspondents say, that their differences in opinion became obvious.
He talks respectfully of his elders and how he learned from them over frequent, and lengthy, family dinners.
So after 11 hours, 12 plays, numerous brief connecting pieces, and lengthy lunch and dinner breaks, does a theater-goer feel noble or entertained or just exhausted by The Great Game: Afghanistan?
