centennial

Centennial is a term used to indicate a period of 100 years or, more commonly, the 100th anniversary of a person, event, or institution. As an adjective, it describes things relating to a century; as a noun, it can refer to the anniversary itself or a celebration held to mark that anniversary. The word derives from Latin centum for hundred and the suffix -ennial (from annus, year). In English usage, centenary is the more common British form for the 100-year anniversary, while centennial is widely used in American English; both senses may apply to a centennial year or event.

The concept is employed in commemorations, history, and branding. A centennial anniversary is often marked by ceremonies, publications, and exhibitions. It may prompt the establishment of museums, monuments, or parks, and can influence cultural and civic projects. Notable historical examples include the Centennial Exposition of 1876 in Philadelphia, the first official World's Fair in the United States held to celebrate the country’s 100-year mark, and the Centennial Olympic Park in Atlanta, created to commemorate the centennial of the modern Olympic Games.

In addition to anniversaries, Centennial appears in geographic and organizational names, used to signify a place, facility, or entity established to honor a 100-year milestone. The term thus functions both as a descriptor of time and as a label in memorial and civic contexts. See also centenary, centuriation.