What does centennially mean?
"Centennially" is a formal adverb meaning once every hundred years or in a way connected with a hundredth anniversary. Derived from the Latin root centum, meaning "hundred," via the adjective "centennial," it belongs to the same word family as "century" and "centenary." The word appears most often in historical, institutional, and commemorative contexts—for example, describing how an organization honors its founding centennially or how a rare astronomical event recurs at hundred-year intervals. Because it is uncommon in casual conversation, speakers usually substitute plain phrases such as "every hundred years." When it does appear, however, "centennially" lends writing a precise, dignified tone suited to ceremonies, milestones, and long-span chronologies. It should not be confused with "centenarian," which refers to a person aged one hundred or more. For anyone writing about anniversaries or century-scale history, it offers an economical, elegant alternative to longer constructions.
adverbOnce every hundred years; in a way that relates to or occurs at the interval of a century.
- At intervals of one hundred years.
- In a manner relating to or characteristic of a hundredth anniversary or centennial celebration.
"The town celebrates its founding centennially, with festivities marking each hundredth year."
"The comet's appearance was recorded centennially by astronomers across three centuries."
"The institution marked the occasion centennially, honoring a tradition begun with its founding."
Built from the same Latin root as 'century,' this rare adverb lets you say in one word what would otherwise take four: it happens once every hundred years.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of centennially
"Centennially" derives from "centennial," which traces to the Late Latin centennialis, from centennis meaning "of a hundred years," built on the Latin centum, "hundred." The root centum also gives English "century" and "centenary," making these close cognates. As the adverbial form of "centennial," it developed alongside that adjective in modern English usage, particularly in the context of anniversary celebrations.
Related word forms
How centennially is actually used
"Centennially" is a formal, relatively rare adverb used chiefly in historical, institutional, or commemorative writing. In everyday speech, writers typically prefer phrases like "once a century" or "every hundred years." It carries a dignified, ceremonial connotation and is most natural when discussing anniversaries, recurring commemorations, or long-interval phenomena.
Easily confused with centennially
"Centennial" is the adjective or noun referring to a hundredth anniversary itself, while "centennially" is the adverb describing something that happens once every hundred years.
A "centenarian" is a person who has lived to be one hundred years old, whereas "centennially" describes events occurring at hundred-year intervals.