须

• Pinyin: xū
• Hanzi breakdown: 须 = 彡 (hair strokes) + 页 (head) — originally beard; classical extension to 'necessity'

Meaning

Must; need to; have to. Expresses necessity or obligation, often in formal written contexts.

A formal auxiliary used in official documents, regulations, and literary writing to indicate that something is required or obligatory. Stronger and more formal than 需要 in written registers.

Examples

1. 参加本次考试者须提前三十分钟到达考场并凭有效证件入场。 All exam takers must arrive at the test site thirty minutes early and enter with valid identification.
2. 合同双方须在协议生效前完成全部法律审核程序，否则协议无效。 Both parties to the contract must complete all legal review procedures before the agreement takes effect; otherwise, the agreement is void.
3. 工程施工期间须严格遵守安全规程，任何违规行为将依规处理。 During construction, all safety regulations must be strictly observed; any violations will be handled in accordance with the rules.

Usage Guide

Context: law, regulations, official documents, academic

Tone: authoritative

Do Say

• 申请人须在截止日期前提交完整材料，逾期将不予受理。(Applicants must submit complete documents before the deadline; late submissions will not be accepted.)
• 所有设备须经过专业人员检验合格后方可投入使用。(All equipment must pass professional inspection before being put into service.)

Don't Say

• 我须去买东西 — 须 is formal/written; use 需要 or 得 in everyday speech; 须 in casual contexts sounds stiff and archaic

Origin & History

须 originally depicted beard hair (面部须毛), extended to mean 'necessarily/must' through classical usage

Cultural Context

Era: Classical to Modern

Generation: All ages

Social background: Universal