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

The fentanyl recovered amounted to 19,500 lethal doses, according to the sheriff’s office. — Kendrick Calfee, Kansas City Star, 21 Aug. 2026

As poor residents poured into the streets in the wake of government austerity measures, the state responded with lethal force. — Tibisay Zea, Christian Science Monitor, 21 Aug. 2026

Bannerman centers on the eponymous Paul Bannerman, a lethal covert operative who convinces a group of the world’s most deadly assassins to quit the spy game for a chance to lead normal lives in the suburbs of Connecticut. — Nellie Andreeva, Deadline, 20 Aug. 2026

Even so, 2026, which, thus far, has featured five lethal heat waves and a historic spate of destructive wildfires, has triggered alarm across the Continent, and beyond. — Eric Klinenberg, New Yorker, 20 Aug. 2026