Malign seems great, but it carries connotations of deliberate evil (like "malevolent").

Fatal or terminal might work, but aren't specific enough.

closed as off-topic by Xanne, JJJ, marcellothearcane, jimm101, Mari-Lou A Aug 26 at 20:04

This question appears to be off-topic. The users who voted to close gave these specific reasons:

  • "Questions on choosing an ideal word or phrase must include information on how it will be used in order to be answered. For help writing a good word or phrase request, see: About single word requests" – marcellothearcane, jimm101, Mari-Lou A
  • "Please include the research you’ve done, or consider if your question suits our English Language Learners site better. Questions that can be answered using commonly-available references are off-topic." – Xanne, JJJ
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  • 2
    Why one word? Please supply sentence with blank, – Xanne Aug 22 at 6:33
  • 1
    What do you mean by ‘universally’ fatal? Do you mean that it will always cause death (e.g., lack of oxygen), or that it will cause death on a universal scale (e.g., giant meteor hitting the earth, wiping out life as we know it)? – Janus Bahs Jacquet Aug 22 at 7:25
  • Context would also indicate whether a word referencing a specific kind of death would fit, such as "toxic" (which refers to poisoning), or "terminal" (which refers to illness). – Stuart F Aug 22 at 16:27

In my experience the word Lethal may be a good choice here.


Three words starting with C in a roughly ascending order of magnitude.

calamitous - a serious accident or bad event causing damage or suffering

catastrophic - a sudden event that causes very great trouble or destruction

cataclysmic - an event that causes a lot of destruction, or a sudden, violent change

Definitions courtesy of Cambridge Dictionary

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