deadly, mortal, fatal, lethal mean causing or capable of causing death. deadly applies to an established or very likely cause of death.

1. causing or tending to cause death; lethal. 2. aiming to kill or destroy; implacable: a deadly enemy. 3. like death. 4. excruciatingly boring. 5. excessive; inordinate: deadly haste.

Add to word list dangerous and able to kill: a deadly poison (Definition of deadly from the Cambridge Academic Content Dictionary © Cambridge University Press)

Find 100 different ways to say DEADLY, along with antonyms, related words, and example sentences at Thesaurus.com.

DEADLY definition: causing or tending to cause death; fatal; lethal. See examples of deadly used in a sentence.

If you describe a person or their behaviour as deadly, you mean that they will do or say anything to get what they want, without caring about other people.

Definition of deadly adjective in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.

Synonyms: deathly, fatal, lethal, mortal, killer, more... Collocations: a deadly [virus, illness], a deadly attack on [Paris], the deadly attack on [Monday], more...

Oct 8, 2025 · deadly (comparative deadlier or more deadly, superlative deadliest or most deadly) (obsolete, rare) Subject to death; mortal. quotations

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 …