The Collaborative International Dictionary of English v.0.48:
dininghall \dininghall\, dining-hall \dining-hall\, dining hall \dining hall\n. a large room at a college or university, used especially for dining. [WordNet 1.5] diningroomWordNet (r) 3.0 (2006):
dining-hall n 1: a large room at a college or university; used especially for dining