What is the one-word name for America’s 250th anniversary?

The one-word name for America’s 250th anniversary is semiquincentennial.

A semiquincentennial is a 250th anniversary. The word is built from semi-, meaning half, and quincentennial, meaning a 500th anniversary. In the United States, it refers specifically to the anniversary of the Declaration of Independence in 2026.

The word is less familiar than bicentennial, which means 200th anniversary and described the 1976 celebration. Other historical alternatives appear in reference works, including sestercentennial and quarter millennium, but semiquincentennial is the standard official name used for the 2026 commemoration.

America250 is the branding used by the United States Semiquincentennial Commission and its national programs. The anniversary name describes the age of the nation’s independence, not the age of the Constitution, which was signed in 1787 and therefore reaches 250 years in 2037.