JS Tip 490: Semi-annual and Bi-annual

From the Writing Workshops: Semi-annual and Bi-annual

Last week, we explored semi-weekly and bi-weekly. (Our counsel: Don’t use the terms.)  

For this week, we promised to explore semi-annual and bi-annual. 

Semi-annual. 

Bi-annual. 

Our counsel: Don’t use the terms. 

They’re too confusing. They mean either twice a year or every two years (or something like that), but almost no one knows which is which.

So— 

Instead of semi-annual, write “twice a year.”

Instead of bi-annual, write “once every two years.”

Bi-annual has an interesting cousin: biennial (notice the e). It’s an attempt to clear up the confusion, and it still means “once every two years.” Can you be sure your reader will understand that? No. Use “once every two years.”

How’s that? 

We didn’t mention perennials. Perennials are nice. Not as colorful as annuals, but still nice. 

If you have suggestions or questions for the tips, let us know. We love this stuff.