Biannual means happening twice each year — once, then again about six months later. A biannual meeting, a biannual magazine, a biannual sale. The pieces are bi- (two) and annual (year).

Biannual means happening twice each yearBiannual的意思是每年發生兩次—— once, then again about six months later一次，然後大約六個月後再一次。A biannual meeting, a biannual magazine, a biannual sale像是biannual meeting、biannual magazine、biannual sale。The pieces are bi- and annual這個字是由bi-和annual組成的： (two)bi-代表『二』， (year)annual代表『年』。

Though actually, English speakers mix this up all the time, even careful ones. Biennial means once every two years, and the two words look almost the same. Some people use biannual both ways, which is why a clear writer often says “twice a year” or “every six months” instead.

Though actually不過其實， English speakers mix this up all the time英語使用者常常搞混這兩個字， even careful ones連細心的人也一樣。Biennial means once every two yearsBiennial的意思是每兩年一次， and the two words look almost the same這兩個字看起來幾乎一模一樣。Some people use biannual both ways有些人把biannual兩種意思都拿來用， which is why a clear writer often says這就是為什麼講究清楚的作者常常會改說 "twice a year" or "every six months" instead『twice a year』或『every six months』。

Semiannual is another word for twice a year and is a little less muddy. You meet biannual in office, school, and magazine English; it is a bit formal, but not rare.

Semiannual is another word for twice a yearSemiannual是另一個表示『一年兩次』的字， and is a little less muddy意思比較不含糊。You meet biannual in office, school, and magazine English你會在辦公室、學校和雜誌的英文裡遇到biannual； it is a bit formal, but not rare它有點正式，但並不罕見。