For America250, what does the term “semiquincentennial” mean?

For America250, “semiquincentennial” means a 250th anniversary. The word combines “semi-,” meaning half, with “quincentennial,” meaning a 500th anniversary. Half of 500 is 250.

The term describes the anniversary of an event that occurred two and a half centuries earlier. America250 uses it for the 250th anniversary of the 1776 founding of the United States, making 2026 the nation’s semiquincentennial year.

A quincentennial is different: it marks 500 years. A bicentennial marks 200 years, while a tricentennial marks 300. The less familiar term “semiquincentennial” is therefore especially useful for distinguishing America’s 250th anniversary from the 200th anniversary celebrated in 1976.

The word is also sometimes shortened informally to “semiquincentenary,” although “semiquincentennial” is the common adjective and noun used in anniversary planning and historical writing.