Below is a list of the Latin Anniversary names.
The root elements of each word are literally multiplied together to create the anniversary name. For example, the word Biennial (an anniversary of 2 years) is broken down as bi- (2) x ennial (years). Sometimes new anniversary names are coined incorrectly by adding the root elements rather than multiplying them, with unfortunate results.
- Annual – 1 year
- Biennial – 2 years
- Triennial – 3 years
- Quadrennial – 4 years
- Quinquennial – 5 years
- Sexennial – 6 years
- Septennial – 7 years
- Octennial – 8 years
- Novennial – 9 years
- Decennial – 10 years
- Undecennial – 11 years
- Duodecennial – 12 years
- Tredecennial – 13 years
- Quattuordecennial – 14 years
- Quindecennial – 15 years
- Vigintennial – 20 years
- Semicentennial – 50 years
- Semisesquicentennial – 75 years
- Centennial – 100 years
While these Latin names are the technically correct terms, in everyday use most people refer to anniversaries by their more familiar material names — such as the silver anniversary (25 years) or the golden anniversary (50 years). The Latin names are most commonly encountered in formal writing, historical documents, and academic contexts.
The Latin naming system shares roots with many familiar English words. Bi-cycle (two wheels), tri-angle (three angles), and dec-ade (ten years) all share their prefix roots with the anniversary names above. This makes the pattern considerably easier to remember once you spot it.
You may also notice that several of the names are still in everyday use in English: Annual (yearly), Biennial (every two years), Triennial (every three years), Decennial (every ten years) and Centennial (every hundred years) are all commonly used words with their Latin anniversary meanings intact.