不一定

• Pinyin: bù yī dìng
• Hanzi breakdown: 不 (bù) — not; 一 (yī) — one; 定 (dìng) — fixed, certain

Meaning

Not necessarily; not certain. Used to express that something is possible but not guaranteed.

A common adverb used to soften assertions or challenge assumptions. Often placed before a verb or adjective to express uncertainty or to politely disagree with a statement.

Examples

1. 明天不一定下雨，我们可以出去玩。 It might not rain tomorrow — we can go out and have fun.
2. 便宜的东西不一定不好。 Cheap things are not necessarily bad.
3. 他不一定能来，因为他很忙。 He might not be able to come because he's very busy.

Usage Guide

Context: everyday speech, expressing uncertainty, polite disagreement

Tone: tentative

Do Say

• 这个办法不一定有用。(This method might not work.)
• 周末不一定有空。(I'm not necessarily free on the weekend.)

Don't Say

• 不一定他不来 — this word order is awkward. Say 他不一定来 (He might not come) with the subject before 不一定.

Origin & History

Compound of 不 (not) and 一定 (certainly, definitely). Literally 'not certainly.'

Cultural Context

Generation: All ages

Social background: Universal