lethal

Compared meaning: capable of causing death (adjective).

比较义项：致命的、能致人死亡的（形容词）。

• deadly

  Describes something with a general, often frightening potential to kill; used broadly and sometimes for emphasis, not necessarily something that has actually killed anyone.

  泛指某事物具有令人恐惧的、笼统的致命危险，用法较宽泛，有时带夸张语气，不一定是已经造成过死亡的事。

  The deadly virus spread quickly through the crowded refugee camp.

  这种致命的病毒在拥挤的难民营中迅速传播。

• fatal

  Describes an event, action, or mistake that actually resulted in death or ruin; typically used after the fact about accidents, injuries, or errors.

  指某一事件、行为或错误确实导致了死亡（或严重后果），通常用于事后描述事故、伤害或错误。

  Ignoring the storm warning turned out to be a fatal mistake for the captain.

  无视暴风雨警告最终成了船长致命的错误。

• terminal

  Used almost only for illnesses that are incurable and expected to end in death eventually; a formal, medical word, not used for weapons, accidents, or storms.

  几乎只用于无法治愈、终将致死的疾病，是较正式的医学用语，不用于武器、事故或暴风雨。

  After the terminal diagnosis, she decided to spend her final months traveling.

  在得到绝症的诊断后，她决定用最后的几个月去旅行。

• lethal 本词

  A more technical, objective word for the capacity to kill, common with doses, weapons, and force; less emotional than deadly.

  语气更客观、技术性更强，常用于描述剂量、武器或武力的致命程度，感情色彩比 deadly 弱。

  The lethal dose of the poison was reached within minutes of ingestion.

  服毒后几分钟内就达到了致命剂量。

All four words mean able to cause death. Deadly suggests general, frightening danger. Fatal describes an event or mistake that caused death. Terminal names an incurable illness, a formal medical word. Lethal is technical, common with doses or weapons. Not compared: terminal meaning computer terminal.

这四个词都可以表示“会致命”，但语气、用法和搭配不同：deadly 强调笼统而令人恐惧的致命危险，常用于渲染气氛；fatal 多用于事后描述已经造成死亡或严重后果的事件；terminal 几乎只用于无法治愈、终将致死的疾病，是较正式的医学用语；lethal 更客观、技术性强，常用于描述剂量、武器或武力。这里不比较 terminal 的其他常见含义，如“（机场、电脑）终端”或“末端的”。