Biannual vs. semiannual vs. biennial

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.