Of or relating to a hundredth anniversary; centennial
The hundredth anniversary of a significant event; a centennial
A celebration of such an anniversary
centennial: of or relating to or completing a period of 100 years; "centennial celebration"
centennial: the 100th anniversary (or the celebration of it)
A century (from the Latin centum, meaning one hundred) is one hundred consecutive years. It is also a Roman term. Centuries are numbered ordinally in English and many other languages (e.g. "the seventh century AD/CE").