adjective, noun, plural ter·cen·ten·ar·ies.
- tricentennial.
adjective
- of or relating to a period of 300 years
- of or relating to a 300th anniversary or its celebration
noun plural -tenaries or -tennials
- an anniversary of 300 years or its celebration
n.1844, “pertaining to a period of 300 years,” from ter- “three times” + centenary.