quatercentenary

noun

qua·​ter·​cen·​te·​na·​ry ˌkwä-tər-sen-ˈte-nə-rē  -ˈsen-tə-ˌner-ē 

-sen-ˈtē-nə-rē

: a 400th anniversary or its celebration

Word History

Etymology

Latin quater four times + English centenary — more at quaternion

First Known Use

1883, in the meaning defined above