deadly

[ded-lee]

adjective

deadlier, deadliest 

1. causing or tending to cause death; fatal; lethal.

   a deadly poison.

2. aiming to kill or destroy; implacable.

   a deadly enemy.

3. like death.

   a deadly pallor.

4. excruciatingly boring.

   The dinner party was absolutely deadly.

   Synonyms: dreary, tedious, dull

5. excessive; inordinate.

   deadly haste.

6. extremely accurate.

   Annie Oakley was a deadly shot.

adverb

1. in a manner resembling or suggesting death.

   deadly pale.

2. excessively; completely.

   deadly dull.

deadly

/ ˈdɛdlɪ /

adjective

1. likely to cause death

   deadly poison

   deadly combat

2. informal,  extremely boring

adverb

1. like death in appearance or certainty

   deadly pale

   a deadly sleep

Other Word Forms

• deadliness noun
• nondeadly adjective

Word History and Origins

Origin of deadly¹

First recorded before 900; Middle English deedli(ch), Old English dēadlīce; dead, -ly

Synonym Study

See fatal.

Example Sentences

When federal prosecutors arrested a man Wednesday on suspicion of setting a small fire that reignited days later into the deadly Palisades blaze, they suggested the arrest largely settled the matter of blame.

Read more on Los Angeles Times

It will find new cures for deadly diseases, solve climate change and invent an inexhaustible supply of clean energy, they argue.

Read more on BBC

The attorney general’s office closed the case in spring 2024, determining the shooters acted in self-defense under the state’s stand-your-ground law, which allows lethal force against deadly threats.

Read more on Wall Street Journal

Investigators zeroed in on irregular air-traffic-control staffing in that deadly crash.

Read more on Wall Street Journal

Spain's weather agency on Thursday issued its highest alert for heavy rains in Alicante in the eastern region of Valencia, where deadly floods struck last year, warning of "extraordinary danger".

Read more on Barron's

Related Words

• bloody 
• carcinogenic 
• cruel 
• dangerous 
• destructive 
• fatal 
• harmful 
• lethal 
• malignant 
• mortal 
• murderous 
• noxious 
• pernicious 
• poisonous 
• savage 
• suicidal 
• toxic 
• violent 
• virulent