lethal
Americanadjective
-
able to cause or causing death
-
of or suggestive of death
Synonym Usage
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.
But it is debatable how many human soldiers you need these days and Woodburn said a new era of autonomous lethal weaponry was close at hand.
From BBC ● Jul. 23, 2026
Research has found acetamiprid can poison honeybees, affecting their foraging capacity and memory, while a 2024 study suggested flupyradifurone could be lethal to some bees.
From Barron's ● Jul. 21, 2026
When I was 11, I would lock myself in my room and play the James Bond soundtracks with those lethal John Barry melodies and the larger-than-life voices of Shirley Bassey and Nancy Sinatra.
From Los Angeles Times ● Jul. 21, 2026
Animals consistently show fear when people pose a direct lethal threat, such as through hunting or fishing.
From Science Daily ● Jul. 15, 2026
Cade Hernandez was the kind of kid you’d dedicate hundred-foot-high monuments to, just so he wouldn’t kill you with his lethal powers of annoyance.
From "100 Sideways Miles" by Andrew Smith
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.
