密封

• Pinyin: mì fēng
• Hanzi breakdown: 密 = 宀 (roof/cover) + 必 (must, phonetic) — airtight, close; 封 = 土 (earth) + 寸 (inch) — to seal, to close off

Meaning

To seal airtight; to hermetically seal. To close something so completely that no air, liquid, or external substance can enter or escape.

Used in engineering, food preservation, laboratory science, and legal/official contexts (sealed documents or envelopes). Implies complete closure with no permeability. Distinct from 封闭 (closed off) in that 密封 specifically emphasises the airtight or impermeable nature of the seal.

Examples

1. 食品加工厂采用真空密封技术来延长产品保质期，同时有效防止细菌污染和氧化变质。 The food processing plant uses vacuum-sealing technology to extend shelf life while effectively preventing bacterial contamination and oxidation.
2. 这批考卷必须在密封的信封中保存，任何拆封行为都将被视为严重违规，相关人员将承担法律责任。 These exam papers must be kept in sealed envelopes; any unsealing will be treated as a serious violation, and those involved will bear legal responsibility.
3. 实验室要求所有化学试剂在使用后立即密封储存，以防止挥发性气体扩散，确保操作环境的安全。 The lab requires all chemical reagents to be sealed and stored immediately after use to prevent volatile gases from spreading and to ensure a safe working environment.

Usage Guide

Context: engineering, food industry, science, legal, logistics

Tone: neutral

Do Say

• 该型号的潜水设备采用了多层密封结构，即使在水下三百米的高压环境中，也能确保内部精密仪器的正常运作。(This model of diving equipment uses a multi-layer hermetic sealing structure that can ensure the normal operation of precision instruments inside even in the high-pressure environment three hundred metres underwater.)
• 药品监管部门规定，所有出厂药品必须经过密封检测，任何包装存在微小缺陷的批次一律不得流入市场。(The pharmaceutical regulatory authority stipulates that all outgoing medicines must undergo sealing inspection; any batch with even a minor packaging defect must not be allowed onto the market.)

Don't Say

• 将'密封'与'关闭'或'封锁'混用 — 密封强调不透气、不渗漏的物理状态，描述一般性的关闭或封锁应用'关闭''封锁'或'封存' (Do not confuse 密封 with 关闭 or 封锁 — 密封 emphasises an airtight, impermeable physical state; use 关闭, 封锁, or 封存 for general closure or blockage)

Origin & History

密 = 宀 (roof) + 必 (must, phonetic) — close, airtight; 封 = 土 (earth/soil) + 寸 (inch) — to seal, to close. Together: to close tightly, leaving no opening.

Cultural Context

Generation: All ages

Social background: Universal