Something that happens once a century.
Something that happens every six years is sexennial.
Biennial or biannual can refer to something which happens every two years.
The Olympics is an event that happens once every 4 years, bringing together athletes from around the world to compete in various sports.
a leap year
bicentennial means when something happens twice in a year, or once every two years
Some things that happen once every four years include: - Leap Years - US Elections - The Olympics
twice-a-day or it can be called semi-diurnal which relates to such occurrences as tides.
A millennium happens once every thousand years.
THAT YOUR AGE ON THIS DAY IS2022
The phrase "once every 3 years" can be expressed as "triennial." This term refers to an event or occurrence that happens every three years. Alternatively, you could also say "every three years" for clarity.
The answer is quadrennially.Quadrennially is defined as something that happens once every four years. Or something which lasts four years.For example, the Olympics are held quadrennially (every 4 years).