centennial
adj. B2 Upper Intermediate US //sɛnˈtɛniəɫ// UK //sɛntˈɛnɪəl// cen·ten·ni·al
adj. relating to the 100th anniversary of an event. You use this word to describe something that happens once every hundred years.
adj. relating to or occurring on the 100th anniversary of a significant event. Often used attributively before a noun.
The city held a grand centennial parade.
The university celebrated its centennial with a week of lectures and alumni reunions.
The centennial exhibition showcased artifacts that traced the nation's evolution from a colonial outpost to a modern industrial power.
From Late Latin centennis (“100-year”) + -al.
Usage
Can also function as a noun referring to the 100th anniversary itself.