lethal
Americanadjective
-
able to cause or causing death
-
of or suggestive of death
Related Words
See fatal.
Other Word Forms
Etymology
Origin of lethal
First recorded in 1575–85; from Latin lētālis, equivalent to lēt(um) “death” + -ālis -al 1; spelling (hence pronunciation) with -h- by association with Greek lḗthē “oblivion”; see Lethe ( def. )
Explanation
Lethal refers to anything dangerous enough to cause death. The cobra's venom is so lethal that if you get bitten and can't find the antidote, it's lights out forever. Poisonous spiders, guns, knives, and radiation — all of these things can be lethal because they have the ability to kill. Even some substances that on their own aren't dangerous can become lethal in large quantities. Eating a peanut butter sandwich won't hurt most people, but it can be lethal to those with a nut allergy. Words like deadly and fatal have meanings that are similar to lethal.
Vocabulary lists containing lethal
100 SAT Words Beginning with "J," "K," and "L"
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A Long Way Gone
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Silent Spring
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
In a letter to CEO Sundar Pichai, those workers said they wanted to avoid AI being used “in inhumane or extremely harmful ways,” such as for lethal weapons or mass surveillance.
From MarketWatch • May 1, 2026
Lawmakers may also raise Hegseth's conflict with artificial intelligence firm Anthropic, which refused to allow its AI models to be used for mass surveillance of civilians or in fully autonomous lethal military operations.
From Barron's • Apr. 29, 2026
The memo also defends the use of lethal injection, calling the drug pentobarbital "the gold standard of lethal injection drugs".
From BBC • Apr. 24, 2026
Inmates have challenged the use of lethal injections in the past on the grounds they may violate Eighth Amendment protections against cruel and unusual punishment.
From The Wall Street Journal • Apr. 24, 2026
Any lethal attack would merely render him deadish, and an ambudrone would arrive within minutes to take him to be revived.
From "Scythe" by Neal Shusterman
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
