严密

• Pinyin: yán mì
• Hanzi breakdown: 严 = strictness/tightness components; 密 = 宀 (roof — enclosed space) + 必 (must/certainly — something that is surely closed off and concealed within)

Meaning

Tight; thorough; airtight; watertight. Describes something meticulously arranged with no gaps, loopholes, or weaknesses. Can also function as a verb meaning to make something more thorough or airtight.

Used to describe logical arguments (逻辑严密 = airtight reasoning), security arrangements (严密监控 = tight surveillance), organisational structures (组织严密 = tightly organised), and physical seals (严密封闭 = sealed airtight). The combination of thoroughness and the absence of gaps is the core meaning. Compare 严格 (strict in enforcement) and 严谨 (rigorous in approach).

Examples

1. 警方在案发现场周围部署了严密的封锁圈，对所有进出人员和车辆进行逐一盘查，不留任何漏洞。 Police set up a tight perimeter around the crime scene and checked every person and vehicle entering or leaving, leaving no loopholes.
2. 这篇论文的论证结构极为严密，从研究假设的提出到实验数据的分析，每一环节都相互支撑，无懈可击。 The argument structure of this paper is extremely rigorous. From the research hypothesis to the analysis of experimental data, every step supports the next—airtight.
3. 工程师对该承压容器的焊接部位进行了严密检测，确认所有接缝均达到工业密封标准后才允许投入使用。 The engineer carried out a rigorous inspection of the pressure vessel’s welded joints and only approved it for use after confirming every seam met industrial sealing standards.

Usage Guide

Context: security, law, academic writing, engineering

Tone: neutral

Do Say

• 该研究所对核心实验室实施严密的安全管控，访客须经过多重身份核验及安全培训方可获准进入。(The institute maintains tight security control over the core laboratory; visitors must pass multiple identity verifications and complete safety training before being granted entry.)
• 检察官认为，辩护方提出的证据链存在明显断层，无法构成在逻辑上严密自洽的无罪辩护。(The prosecutor argued that the chain of evidence presented by the defence contained an obvious gap and could not constitute a logically airtight and internally consistent case for acquittal.)

Don't Say

• 他很严密 — 严密 describes situations, structures, arguments, or security measures, not people directly; for a person who is thorough and meticulous use 严谨 or 缜密; saying 他很严密 sounds awkward and unnatural

Origin & History

严 (strict/tight) + 密 (dense/tight/secret) — both components reinforce the idea of something with no gaps

Cultural Context

Era: Modern

Generation: All ages

Social background: Universal