What term describes the 250th anniversary commemorated by the United States Semiquincentennial?

The term describing the 250th anniversary commemorated by the United States Semiquincentennial is semiquincentennial.

The word combines elements meaning half and five hundred, producing a term for half of five centuries, or 250 years. It is the formal name used for the United States’ 250th-anniversary commemoration, while America250 is the shorter branding used for many related programs.

Several alternative terms exist. Bisesquicentennial combines roots associated with two hundred and fifty, while sestercentennial and quarter millennium are also used. These alternatives are much less familiar in ordinary American usage.

The name can be confused with bicentennial, which means a 200th anniversary and was used for the nationwide celebrations in 1976. A tricentennial means a 300th anniversary, so neither term describes the 2026 observance.