the world cup ( I think) happens every 3 years or 4 years?
Tri-annual.
Every century means every 100 years
I assume you mean every four years and yes it is held every four years
'triennial'
The word Biennial means Every two years
"Decentennial" is not a recognized English word. It may be a misspelling or a made-up term. If you meant "decennial," it refers to something that occurs once every ten years.
Every 2 years
I think they take place every 3 years..... I'm not sure, srry
every 3 months
about every 3 years
every 3 years
Annually mean every year.
3 years