tricentennial

tricentennial [trahy-sen-ten-ee-uh l] Word Origin adjective

1. pertaining to 300 years or a period of 300 years.
2. marking the completion of such a period: a tricentennial celebration.

noun

3. a 300th anniversary or its celebration.

Also tercentenary, tercentennial. Origin of tricentennial First recorded in 1880–85; tri- + centennial