Available Definitions:
1) a. - Relating to, or associated with, the commemoration of an event that happened a hundred years before; as, a centennial ode.
2) a. - Happening once in a hundred years; as, centennial jubilee; a centennial celebration.
3) a. - Lasting or aged a hundred years.
4) n. - The celebration of the hundredth anniversary of any event; a centenary.