quatercentenaryquat‧er‧cen‧te‧na‧ry /ˌkwætəsenˈtiːnəri $ ˌkwɑːtərsenˈten-/ noun (plural quatercentenaries) [countable] 
the day or year exactly 400 years after a particular eventquatercentenary of
the quatercentenary of Shakespeare’s birth
the day or year exactly 400 years after a particular eventquatercentenary of the quatercentenary of Shakespeare’s birth