Possible Duplicate:
If annual means one year, is there any word for two,three, four.. year
...like Olympic Games or World Cup. Is there a word to describe their periodical characteristic or just simply "every 4 year"? There are words like Annual, Biennial, Triennial (every 1, 2, 3 years) but Quadennial seems not to be a valid word.
quadrennialin that question. But it does not appear in Oxford or Cambridge dictionaries. Is it OK if I use it in academic writing? – KiL Aug 29 '12 at 05:01