Quadrennial (adjective)

1. Happening once every four years.
2. Relating to a period of four years.

Origin:

Late 16th century: from latin quadriennium "a period of four years", from quadri- "four" + annus "year".

Examples:

1. The Olympic Games are a quadrennial event.
2. The country holds quadrennial elections to choose its president.
3. The quadrennial budget is reviewed and updated every four years.
4. The quadrennial cycle of growth and decay is a recurring pattern in nature.
5. The quadrennial plan of the company outlines its goals and strategies for the next four years.