Webster's Revised Unabridged Dictionary · 1913

Centennial

Centennial , adjective

[Latin centum a hundred + annus year.]

1.
Relating to, or associated with, the commemoration of an event that happened a hundred years before; as, a centennial ode.
2.
Happening once in a hundred years; as, centennial jubilee; a centennial celebration.
3.
Lasting or aged a hundred years.
That opened through long lines Of sacred ilex and centennial pines. — Longfellow

Centennial , noun

The celebration of the hundredth anniversary of any event; a centenary. [United States]