ˌSunday ˈlunch BrE AmE ( also ˌSunday ˈdinner ) noun [uncountable]
in the UK, a large traditional meal that is typically eaten at about one o'clock on a Sunday afternoon, with the whole family sitting together
SUNDAY LUNCH
Meaning of SUNDAY LUNCH in English
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012