Synonyms of lethal

lethal

adjective

ˈlē-thəl 

as in deadly

likely to cause or capable of causing death

we were lucky that the snake's venom wasn't lethal, and our friend turned out to be all right

Synonyms & Similar Words

• deadly
• fatal
• poisonous
• infectious
• infective
• killer
• harmful
• toxic
• dangerous
• murderous
• deathly
• terminal
• mortal
• destructive
• baleful
• hazardous
• injurious
• vital
• fell
• deleterious
• pernicious
• pestilent
• virulent
• baneful
• risky
• noxious
• sublethal
• serious
• perilous
• pestilential
• threatening
• menacing
• truculent
• ugly
• bloody
• unhealthy
• sanguinary
• grievous
• grave
• parlous
• unsound
• sanguine
• jeopardizing
• internecine

Antonyms & Near Antonyms

• healthy
• nonlethal
• beneficial
• healthful
• nonfatal
• wholesome
• salutary
• salubrious
• restorative
• curative
• corrective
• useful
• remedial
• advantageous
• tonic
• safe
• nontoxic
• alleviative
• nonpoisonous

Synonym Chooser

How does the adjective lethal differ from other similar words?

Some common synonyms of lethal are deadly, fatal, and mortal. While all these words mean "causing or capable of causing death," lethal applies to something that is bound to cause death or exists for the destruction of life.

lethal gas

When is deadly a more appropriate choice than lethal?

The words deadly and lethal can be used in similar contexts, but deadly applies to an established or very likely cause of death.

a deadly disease

When could fatal be used to replace lethal?

Although the words fatal and lethal have much in common, fatal stresses the inevitability of what has in fact resulted in death or destruction.

fatal consequences

When might mortal be a better fit than lethal?

While in some cases nearly identical to lethal, mortal implies that death has occurred or is inevitable.

a mortal wound

Example Sentences

Recent Examples of lethal

International organizations swiftly condemned the lethal crackdown by police and called for an independent investigation. —Sugam Pokharel, CNN Money, 9 Sep. 2025

Getty Images Despite touting two of the greatest offensive players the NBA has ever seen in LeBron James and Luka Doncic, and another burgeoning one who becomes more and more lethal with each passing season in Austin Reaves, the Los Angeles Lakers aren’t yet a true inner circle contender. —Mat Issa, Forbes.com, 8 Sep. 2025

Both involve a lethal contest put on for spectacle to exploit the poor. —Nick Romano, Entertainment Weekly, 8 Sep. 2025

Tests then confirmed he'd been given a potentially lethal dose of the drug lidocaine. —Becca Longmire, People.com, 8 Sep. 2025