cen·ten·ni·al 
(sĕn-tĕnē-əl)
(sĕn-tĕnē-əl)adj.
1. Of or relating to an age or period of 100 years.
2. Occurring once every 100 years: a centennial commemoration.
3. Of or relating to a 100th anniversary.
n.
A 100th anniversary or a celebration of it.
[Latin centum, hundred; see dek in the Appendix of Indo-European roots + (BI)ENNIAL.]
cen·tenni·al·ly adv.