Did You Know?
When we describe something as "biannual," we can mean either that it occurs twice a year or that it occurs once every two years. So how does someone know which particular meaning we have in mind? Well, unless we provide them with a contextual clue, they don't. Some people prefer to use "semiannual" to refer to something that occurs twice a year, reserving "biannual" for things that occur once every two years. This practice is hardly universal among English speakers, however, and "biannual" remains a potentially ambiguous word. Fortunately, English also provides us with "biennial," a word that specifically refers to something that occurs every two years or that lasts or continues for two years.