Dictionary
tri•cen•ten•ni•al
Pronunciation: (trī"sen-ten'ē-ul), [key]—
adj.
1. pertaining to 300 years or a period of 300 years.
2. marking the completion of such a period:
a tricentennial celebration.
—
n.
a 300th anniversary or its celebration.
Also,tercentenary,tercentennial.Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.