quatercentenary
From Longman Dictionary of Contemporary Englishquatercentenaryquat‧er‧cen‧te‧na‧ry /ˌkwætəsenˈtiːnəri $ ˌkwɑːtərsenˈten-/ noun (plural quatercentenaries) [countable] TMthe day or year exactly 400 years after a particular eventquatercentenary of the quatercentenary of Shakespeare’s birthOrigin quatercentenary (1800-1900) Latin quater “four times” + English centenary