DEADLY Synonyms: 324 Similar and Opposite Words

Q: How does the adjective 'deadly' differ from other similar words?

Some common synonyms of deadly are fatal , lethal , and mortal . While all these words mean "causing or capable of causing death," deadly applies to an established or very likely cause of death. // a deadly disease

Q: When would 'fatal' be a good substitute for 'deadly'?

In some situations, the words fatal and deadly are roughly equivalent. However, fatal stresses the inevitability of what has in fact resulted in death or destruction. // fatal consequences

Q: When is 'lethal' a more appropriate choice than 'deadly'?

While in some cases nearly identical to deadly , lethal applies to something that is bound to cause death or exists for the destruction of life. // lethal gas

Q: When could 'mortal' be used to replace 'deadly'?

The synonyms mortal and deadly are sometimes interchangeable, but mortal implies that death has occurred or is inevitable. // a mortal wound

deadly 1 of 2

adjective

ˈded-lē

Definition of deadly next

as in lethal

likely to cause or capable of causing death the doctors were alarmed about the outbreak of the deadly new virus

Synonyms & Similar Words

Relevance

Antonyms & Near Antonyms

as in sheer

having no exceptions or restrictions the deadly tedium of waiting for the fog to lift

Synonyms & Similar Words

Antonyms & Near Antonyms

as in mortal

of, relating to, or suggestive of death a deadly pallor spread across her face as the tragic news gradually sank in

Synonyms & Similar Words

Antonyms & Near Antonyms

deadly

2 of 2

adverb

as in extremely

to a great degree I'm deadly serious about making an offer on the house

Synonyms & Similar Words

Antonyms & Near Antonyms

Synonym Chooser

How does the adjective deadly differ from other similar words?

Some common synonyms of deadly are fatal, lethal, and mortal. While all these words mean "causing or capable of causing death," deadly applies to an established or very likely cause of death.

a deadly disease

When would fatal be a good substitute for deadly?

In some situations, the words fatal and deadly are roughly equivalent. However, fatal stresses the inevitability of what has in fact resulted in death or destruction.

fatal consequences

When is lethal a more appropriate choice than deadly?

While in some cases nearly identical to deadly, lethal applies to something that is bound to cause death or exists for the destruction of life.

lethal gas

When could mortal be used to replace deadly?

The synonyms mortal and deadly are sometimes interchangeable, but mortal implies that death has occurred or is inevitable.

a mortal wound

Example Sentences

Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.

Recent Examples of deadly

Adjective

Israel's Cabinet approved a deal early Saturday for a ceasefire in Gaza that would release dozens of hostages held there and pause the 15-month war with Hamas, bringing the sides a step closer to ending their deadliest and most destructive fighting ever. —

Samy Magdy, arkansasonline.com, 18 Jan. 2025 Israelis will be required to withdraw from parts of Gaza that were wrested from terrorists after months of deadly urban warfare. —

The Editors, National Review, 17 Jan. 2025

Adverb

But don’t be fooled by the apparent humor, the Hellcat crime group is deadly serious and wants $125,000 in the cryptocurrency Monero as well. —

Davey Winder, Forbes, 6 Nov. 2024 While delivered with a smile, the question was deadly serious in a congressional district with such an even partisan split that anything could happen to knock the future incumbent off kilter two years from now, as just happened to Democratic first-term Rep. Yadira Caraveo. —

John Aguilar, The Denver Post, 12 Nov. 2024 See all Example Sentences for deadly

Recent Examples of Synonyms for deadly

Adjective

Burden is a lethal weapon who plays with slick separation skills, elusiveness, and creativity when the ball is in his hands.

— Lawrence Dow, Fort Worth Star-Telegram, 21 Jan. 2025
This is just one high-profile example of how depression and anxiety disorders, ineffectively treated, can have lethal consequences.

— Kara Margolis, Chicago Tribune, 21 Jan. 2025