What does biannual mean?
Biannual is an adjective which means twice a year.
For example:
Let’s set up a biannual meeting.
What does semiannual mean?
Semiannual is an adjective which also means twice a year.
For example:
Let’s set up a semiannual conference.
What does biennial mean?
Biennial can be an adjective or a noun which means every second year.
For example:
Let’s set up a biennial competition.
What’s the difference between biannual, semiannual and biennial?
Biannual and semiannual both mean twice a year. To say once every two years, use biennial instead.