lethal

1 of 2

adjective

le·​thal ˈlē-thəl 

1

a

: of, relating to, or causing death

death by lethal injection

b

: capable of causing death

lethal chemicals

2

: gravely damaging or destructive : devastating

a lethal attack on his reputation

3

: very potent or effective

a lethal fastball

also : having a high alcohol content

a lethal rum punch

lethality

lē-ˈtha-lə-tē 

noun

lethally

ˈlē-thə-lē 

adverb

lethal

2 of 2

noun

1

: an abnormality of genetic origin causing the death of the organism possessing it

2

: lethal gene

Synonyms

Adjective

• baleful
• deadly
• deathly
• fatal
• fell
• killer
• mortal
• murderous
• pestilent
• terminal
• vital

Choose the Right Synonym for lethal

deadly, mortal, fatal, lethal mean causing or capable of causing death.

deadly applies to an established or very likely cause of death.

a deadly disease

mortal implies that death has occurred or is inevitable.

a mortal wound

fatal stresses the inevitability of what has in fact resulted in death or destruction.

fatal consequences

lethal applies to something that is bound to cause death or exists for the destruction of life.

lethal gas

Examples of lethal in a Sentence

Adjective

a potentially lethal dose of a drug

He was sentenced to death by lethal injection.

Recent Examples on the Web

Adjective

The arachnids have become the lethal poisonous animal in Brazil and has increased the demand for antivenom. —Laura Baisas, Popular Science, 7 Nov. 2024

Snares, set to capture other animals for bushmeat, pose a lethal risk to saolas, who often fall victim to these traps accidentally. Cheap and easy to deploy, snares blanket the forests, endangering not just the saola but a wide range of species. —Scott Travers, Forbes, 5 Nov. 2024

Noun

There are already concerns in Australia about the rate of escalation of force at some protests and about the use of less-than-lethal weaponry itself. —Kylie Bourne, Discover Magazine, 14 Sep. 2015

Almost 8 of 10 lethal overdose victims had no contact with the agency before their deaths, the report found. —Washington Post, 4 Sep. 2020

Word History

Etymology

Adjective and Noun

Latin letalis, lethalis, from letum death

First Known Use

Adjective

circa 1604, in the meaning defined at sense 1a

Noun

1917, in the meaning defined at sense 1

Phrases Containing lethal

• lethal gene

Kids Definition

lethal

1 of 2 adjective

le·​thal ˈlē-thəl 

: causing or capable of causing death

lethal chemicals

lethally

ˈlē-thə-lē 

adverb

lethal

2 of 2 noun

: lethal gene

Medical Definition

lethal

1 of 2 adjective

le·​thal ˈlē-thəl 

: of, relating to, or causing death

a lethal injury

also : capable of causing death

lethal chemicals

a lethal dose

lethality

lē-ˈthal-ət-ē 

noun

plural lethalities

lethally adverb

lethal

2 of 2 noun

1

: an abnormality of genetic origin causing the death of the organism possessing it usually before maturity

2

: lethal gene