lethal
Americanadjective
-
able to cause or causing death
-
of or suggestive of death
Related Words
See fatal.
Other Word Forms
- hyperlethal adjective
- lethality noun
- lethally adverb
- lethalness noun
- nonlethal adjective
- nonlethally adverb
- semilethal adjective
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”; 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.
The fish suffered their latest decline during the severe 2020-22 drought, when the water flowing from dams sometimes got so warm that it was lethal for salmon eggs.
From Los Angeles Times • Apr. 12, 2026
Bryan Cranston transitioned from befuddled dad Hal to lethal drug lord Walter White in “Breaking Bad.”
From Los Angeles Times • Apr. 10, 2026
European Command to support other combatant commands with “critical logistics, ready forces, and lethal capabilities,” and that U.S. power projection depends on European allies.
From The Wall Street Journal • Apr. 6, 2026
Higher energy prices have the potential to cause stagflation —a lethal combination of higher inflation and lower growth that would likely undermine businesses’ bottom lines.
From Barron's • Mar. 27, 2026
In the absence of this protein, blood refuses to clot—and even a small nick or wound can accelerate into a lethal bleeding crisis.
From "The Gene" by Siddhartha Mukherjee
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.
