bi-

bi- — 字首

1. a word beginning that means 'two times in a period' or 'once in every two period

1.字首B1
釋義

每兩次；兩倍

表示每兩次或每兩段時間發生一次的前綴

a word beginning that means 'two times in a period' or 'once in every two periods'. For example, a biweekly magazine comes out every two weeks, while biannual check-ups happen twice a year.

例句

The town publishes a biweekly paper that arrives every other Thursday morning.

鎮上出版一份雙週報，每隔一週的星期四早上送達。

biweekly — every two weeks

Ingrid goes for biannual dental check-ups, once in March and once in September.

Ingrid 每年進行兩次牙科檢查，一次在三月、一次在九月。

biannual — twice a year

同義詞
  • semi-

    means 'half' or 'twice per period'; semiweekly = twice a week (clearer than biweekly)

  • di-

    also means 'two' but used in scientific words like dioxide, not for time periods

用法筆記

This prefix can cause confusion because the same word sometimes means 'twice per period' and sometimes 'every two periods'. In careful writing, use 'semi-' for 'twice per' (semiweekly = twice a week) and 'bi-' for 'every two' (biweekly = every two weeks), though not everyone follows this rule.

常見錯誤

❌The biweekly meeting is on Monday and Thursday.
✅The biweekly meeting is every other Monday.
💡'Biweekly' normally means every two weeks; for twice a week, 'semiweekly' or 'twice-weekly' is clearer.

2. a word beginning that means 'having two of something' or 'involving both sides'.

2.字首B1
釋義

雙；兩

表示具有兩個或涉及雙方的前綴

a word beginning that means 'having two of something' or 'involving both sides'. It appears in words like bilingual (using two languages) and bilateral (affecting two sides equally).

例句

Dr. Okonkwo hired a bilingual receptionist who speaks both English and Igbo fluently.

Dr. Okonkwo 聘請了一位會說英語和伊博語的雙語接待員。

bilingual — speaking two languages

The two countries reached a bilateral trade deal after six months of difficult talks.

兩國經過六個月的艱難談判，達成了雙邊貿易協定。

bilateral — involving two sides

同義詞
  • di-

    also means 'two', used in Greek-derived scientific terms like dioxide, dipolar

  • duo-

    means 'two' and appears in words like duopoly, duotone

反義詞
  • uni-

    means 'one'; unilateral = involving one side only

  • mono-

    means 'one'; monorail = single rail, monolingual = one language

用法筆記

This sense of 'bi-' combines freely with roots to form adjectives and nouns describing things with two parts, sides, or members. It is different from sense 1 (time-related) — here there is no 'per period' meaning, just the idea of twoness.

常見錯誤

❌The biannual agreement between the two countries.
✅The bilateral agreement between the two countries.
💡'Biannual' means twice a year; 'bilateral' means involving two sides.

bi- — 形容詞

bi- — 名詞