A mess hall is what military types call their dining halls.
The term’s origins go back to the Middle Ages when British sailors began calling their meagre, often grub-infested meals a mess, which they clearly were.
Mess originally meant the food for one meal.
It has since evolved to signify a specific area where sailors, soldiers, and aircrew gather to eat, drink, and socialize.
In order to maintain discipline, there are usually three levels of mess: officers, non-commissioned officers (NCOs), and rank-and file soldiers.