lethal
Americanadjective
-
able to cause or causing death
-
of or suggestive of death
Synonym Usage
See fatal.
Other Word Forms
Derived 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.
It possesses the most lethal and far-flung military; it controls the leading currency; its leaders’ words and deeds are more closely observed and analyzed than those of any other leaders.
From Slate • Jun. 8, 2026
If the plan stands, he said, “we know that it’s going to be lethal for some salmon eggs this summer.”
From Los Angeles Times • May 21, 2026
A 1999 report by the Organization of American States’ Inter-American Commission on Human Rights described “the disproportionate and indiscriminate use of lethal force applied to the civilian aircraft.”
From The Wall Street Journal • May 20, 2026
The WHO has said it was alerted to the emergence of a highly lethal disease on May 5, with the first positive Ebola test on May 15.
From Barron's • May 20, 2026
As a result, a less lethal myxo virus spreads baby viruses to more rabbits than did the original, highly virulent myxo.
From "Guns, Germs, and Steel: The Fates of Human Societies" by Jared M. Diamond
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.
