| 必要 | bì yào | necessary / essential / indispensable / required |   |
| 要点 | yào diǎn | main point / essential | |
| 必备 | bì bèi | essential | |
| 必需 | bì xū | to need / to require / essential / indispensable | |
| 必不可少 | bì bù kě shǎo | absolutely necessary / indispensable / essential | |
| 必需品 | bì xū pǐn | necessity / essential (thing) | |
| 至关重要 | zhì guān zhòng yào | extremely important / vital / crucial / essential | |
| 切要 | qiè yào | essential / extremely important | |
| 不可少 | bù kě shǎo | indispensable / essential | |
| 重头 | zhòng tóu | main / most important / essential / important part | |
| 主流 | zhǔ liú | main stream (of a river) / fig. the essential point / main viewpoint of a matter / mainstream (culture etc) | |
| 要素 | yào sù | essential factor / key constituent | |
| 纲要 | gāng yào | outline / essential points | |
| 精油 | jīng yóu | essential oil | |
| 切切 | qiè qiè | urgently / eagerly / worried / (urge sb to) be sure to / it is absolutely essential to (follow the above instruction) | |
| 可有可无 | kě yǒu kě wú | not essential / dispensable | |
| 闪光点 | shǎn guāng diǎn | lit. flash point / crucial point / essential point | |
| 赖氨酸 | lài ān suān | lysine (Lys), an essential amino acid | |
| 蛋氨酸 | dàn ān suān | methionine (Met), an essential amino acid | |
| 因噎废食 | yīn yē fèi shí | lit. not eating for fear of choking (idiom) / fig. to cut off one's nose to spite one's face / to avoid sth essential because of a slight risk | |
| 精氨酸 | jīng ān suān | argnine (Arg), an essential amino acid | |
| 色氨酸 | sè ān suān | tryptophan (Trp), an essential amino acid | |
| 苏氨酸 | sū ān suān | threonine (Thr), an essential amino acid | |
| 卟啉 | bǔ lín | porphyrin (organic chemical essential to hemoglobin and chlorophyll) (loanword) | |
| 亮氨酸 | liàng ān suān | leucine (Leu), an essential amino acid | |
| 组氨酸 | zǔ ān suān | histidine (His), an essential amino acid | |
| 异亮氨酸 | yì liàng ān suān | isoleucine (Ile), an essential amino acid | |
| 本性难移 | běn xìng nán yí | It is hard to change one's essential nature (idiom). You can't change who you are. / Can the leopard change his spots? (Jeremiah 13:23) | |
| 万不得已 | wàn bù dé yǐ | only when absolutely essential (idiom) / as a last resort | |
| 人精 | rén jīng | sophisticate / man with extensive experience / child prodigy / Wunderkind (i.e. brilliant child) / spirit within a person (i.e. blood and essential breath 血氣|血气 / of TCM) | |
| 甲硫氨酸 | jiǎ liú ān suān | methionine (Met), an essential amino acid | |
| 神髓 | shén suǐ | lit. spirit and marrow / the essential character | |
| 精讲多练 | jīng jiǎng duō liàn | a teaching strategy combining a concise explanation of essential concepts with frequent practice | |
| 缬氨酸 | xié ān suān | valine (Val), an essential amino acid | |
| 苯丙氨酸 | běn bǐng ān suān | phenylalanine (Phe), an essential amino acid | |
| 贾思勰 | Jiǎ Sī xié | Jia Sixie, sixth century writer and author of agricultural encyclopedia Essential skill to benefit the people 齊民要術|齐民要术[Qi2 min2 Yao4 shu4] | |
| 风油精 | fēng yóu jīng | essential balm containing menthol, eucalyptus oil etc, used as a mosquito repellant | |
| 齐民要术 | Qí mín Yào shù | Essential skill to benefit the people, sixth century encyclopedia of agricultural knowledge by Jia Sixie 賈思勰|贾思勰[Jia3 Si1 xie2] | |
| 基本服务一揽子方桉 | | Essential Services Package | |
| 区域间必需药品方桉 | | Interregional programme for essential drugs | |
| 必需药品行动纲领 | | Action Programme on Essential Drugs | |
| 基本平衡 | jī běn píng héng | essential parity | |
| 必需药品和疫苗行动纲领 | | Action Programme on Essential Drugs and Vaccines | |
| 基本立法联合委员会 | | Joint Commission on Essential Legislation | |
| 阿富汗妇女基本权利宣言 | | Declaration of the Essential Rights of Afghan Women | |
| 恢复萨拉热窝基本公用事业行动计划 | | Plan of Action to Restore Essential Public Services in Sarajevo | |
| 必要工作人员 | | essential staff / critical staff | |
| 直接和重要军事支援设施 | | direct and essential military support facilities | |
| 坦桑尼亚基本卫生措施项目 | tǎn sāng ní yà jī běn wèi shēng cuò shī xiàng mù | Tanzania Essential Health Interventions Project | |
| 必要技术 | | essential technology | |
| 维持和平利用外层空间必要条件研讨会 | | Symposium on Conditions Essential for Maintaining Outer Space for Peaceful Purposes | |
| 必需药品方桉 | | Essential Drugs Programme | |
| 必需药品价目表 | | essential drugs price list | |
| 必需药品包 | | essential drug kit | |
| 必需药品示范表 | | model list of essential drugs | |
| 必需药品 | | essential drugs | |
| 基本化学品 | | essential chemical | |
| 基本设备清单 | | essential equipment list | |
| 基本学习用品包 | | Essential Learning Package | |
| 儿童和母亲必需药品方桉 | | Programme of Essential Medicines for Children and Their Mothers | |
| 务期 | wù qī | it is essential to (complete a project on time, be thorough etc) | |
