semiquincentennial

American  

[sem-ee-kwin-sen-ten-ee-uhl, sem-ahy-] / ˌsɛm iˌkwɪn sɛnˈtɛn i əl, ˌsɛm aɪ- /

noun

1. a 250th anniversary or its celebration.

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adjective

1. relating to a 250th anniversary or its celebration.

2. lasting or having lasted 250 years; 250 years old.

Explanation

Semiquincentennial is a very long word for a very big anniversary — 2026 is the semiquincentennial, or 250th anniversary, of the United States. Semiquincentennial derives from the Latin words semi, "half," quinque, "five," and centum, "one hundred." You don't need this word very often, since it's rare that a country, building, or organization marks its 250th anniversary, but when you do, it's a big deal. The British Parliament celebrated its semiquincentennial in 1957, and the Taj Mahal was built in 1648, which means its semiquincentennial happened back in 1898.

Example Sentences

As the U.S. prepares to celebrate its semiquincentennial, “War Without Mercy” reminds us that “liberty or death” was more than a popular patriot rallying cry.

From The Wall Street Journal • Jan. 9, 2026

The sold-out gathering at the Strand was one of six tea parties being thrown throughout the country by the publisher to commemorate Austen’s semiquincentennial.

From Los Angeles Times • Dec. 30, 2025

Some excellent books that ratify DeVoto’s enthusiasm have recently appeared, heralding America’s semiquincentennial, the 250th anniversary of the founding of our nation.

From The Wall Street Journal • Nov. 21, 2025

The country is now more than four months into its semiquincentennial, which Atkinson joked “sounds like a medical procedure,” but is actually the 250th anniversary of the founding of the United States.

From Los Angeles Times • Nov. 5, 2025

Geismar’s ambitions for the semiquincentennial design are no less grand.

From Seattle Times • Dec. 4, 2023