不
bù
In real, traceable use. Part of the curated seed collection; community review is coming.
Not, no — the basic negative, placed directly before a verb or an adjective. 不去 is 'not going', 不好 'not good'. The verb 有 'to have' is the exception: it takes 没, giving 没有. Before a fourth tone it is pronounced bú (不是 bú shì), but its dictionary form stays bù. On its own it answers 'no'.
Phó từ phủ định: không, chẳng. Đặt ngay trước động từ hoặc tính từ: 不去 (không đi), 不好 (không tốt). Riêng động từ 有 (có) thì phủ định bằng 没: 没有. Đứng trước thanh 4, 不 đọc thành bú (不是 bú shì), nhưng từ điển vẫn ghi bù. Đứng một mình, 不 là lời đáp “không”.
AdverbRegister: neutral
Examples
Editorial example (illustrative, not a corpus attestation) — awaiting a native-speaker check
Sources & notes
Hán-Việt bridge batch 063 (2026-11-14). Headword, Traditional form and pinyin checked against CC-CEDICT (CC BY-SA 4.0) source ↗ · Hán-Việt reading: Unihan kVietnamese source ↗ · No Vietnamese entry is linked as its twin; the Hán-Việt reading is given character by character. Definition, literal gloss and example sentence are original; the example has not had a native-speaker check yet.
Common questions
What does “不” mean?
Not, no — the basic negative, placed directly before a verb or an adjective. 不去 is 'not going', 不好 'not good'. The verb 有 'to have' is the exception: it takes 没, giving 没有. Before a fourth tone it is pronounced bú (不是 bú shì), but its dictionary form stays bù. On its own it answers 'no'.
Is “不” formal or informal?
不 is generally neutral.