In the U.S., that's the date when Congress counts the electoral votes after a presidential/ vice presidential election.
The President of The United States of America is inaugurated.
A triennial event happens every three years.
Something that happens every six years is sexennial.
Something that happens every three years is a triennialevent.
Something that happens once a century.
As far as I know, nothing special happens every 100,000 years. A full precession cycle takes about 26,000 years.
Quinquennial = something that happens every 5 years. Lustral = also something that happens every 5 years or we could invent: semi-Decennial: where semi is half and Deccennial happens every 10 years.
* New Years Day -- January 1 * MLK Jr Day -- 3rd Monday in January * Inauguration Day -- January 20 (Every 4 years)
It happens every 200 years.
The Olympics.
Something that happens every 5 years
the Olympics