Leap year
die
The Olympics.
Commonwealth Games
You have the world cup, the U.S president is elected, the Olympics are held , and so is the Euro cup. This all happens every four years.
Could it be the Olympics.
February 29 occurs every four years, in years that are divisible by four. This is known as a leap year.
When used as an adjective, it means occurring every, or last for, four years. As a noun, it references an event that occurs every four years. (see: http://dictionary.reference.com/browse/quadrennially )
eclipse
Some things that happen once every four years include: - Leap Years - US Elections - The Olympics
The President of The United States of America is inaugurated.
The Olympics are held once every fourth year.
A leap year happens only once every four years; that is also true of US Presidential elections.
a leap year