Originally Posted by
rickair7777
It's Biennial. Well it used to be. Just "Flight Review" now.
They changed it because too many people didn't know the difference between biennial and bi-annual...
Actually Merriam Webster lists biennial as one of the two definitions of biannual. This is just one of those oddities found in the english language that doesn't make much sense. But it is a correct use of the word nonetheless.