biannual

/baɪˈænjuəl/ (bre, ipa) · /baɪˈænjuəl/ (ame, ipa) · /(ˌ)bī-ˈan-yə(-wə)l/ (ame, mw)

biannual — adjective

  • biannualpositive
  • more biannualcomparative
  • most biannualsuperlative

1. Taking place, appearing, or being paid two times within a single year.

1.形容詞C1
釋義

Taking place, appearing, or being paid two times within a single year.

例句

The school sends biannual progress reports to parents in January and June.

collocation: biannual progress reports

Our club holds a biannual book sale each spring and again in autumn.

timing: twice in the same year

同義詞
  • semiannual

    more precise when you want to make the twice-a-year meaning completely clear

  • half-yearly

    same timing, but less common and slightly more British in tone

反義詞
  • annual

    happening once a year rather than twice within the year

  • monthly

    happening every month rather than only two times a year

用法筆記

Most often used before nouns such as report, sale, bonus, and meeting. In careful modern usage, this sense usually means 'twice a year'; writers who want to avoid ambiguity sometimes choose semiannual instead.

常見錯誤

❌The exam is biannual, so it happens every two years.
✅The exam is biannual, so it happens twice a year.
💡In its main modern use, biannual means two times within one year, not once every two years.

2. Taking place once in every two-year period rather than every year.

2.形容詞C1
釋義

Taking place once in every two-year period rather than every year.

例句

Because the science fair is biannual, ninth-grade students can enter only once before graduation.

meaning: once every two years

The town's biannual art show returns in 2028, two years after the last one.

同義詞
  • biennial

    the clearer and more widely recommended word for this once-every-two-years meaning

反義詞
  • annual

    happening every year instead of after a two-year gap

  • semiannual

    happening twice in one year rather than once in two years

用法筆記

This older or disputed use means 'once every two years'. Many style guides recommend biennial instead, because readers often understand biannual as 'twice a year'.

常見錯誤

❌The festival is biannual, so we see it two times every year.
✅The festival is biannual, so we see it once every two years.
💡In this disputed sense, biannual refers to an event that returns after a two-year gap.