A fancy word for a dining hall, or a place for communal meals, is a refectory. It is usually used to describe a dining hall in a religious institution, like where monks eat together.
The word refectory comes from the Latin word reficere which means "to restore, renew." A meal together is a great way of restoring unity to a group. Nothing renews community like a great dinner, and the conversation that occurs around it. Lunch in your school's refectory? Maybe not so much.