[ ded-lee ]
See synonyms for: deadlydeadliest on

adjective,dead·li·er, dead·li·est.
  1. causing or tending to cause death; fatal; lethal: a deadly poison.

  2. aiming to kill or destroy; implacable: a deadly enemy.

  1. like death: a deadly pallor.

  2. excruciatingly boring: The dinner party was absolutely deadly.

  3. excessive; inordinate: deadly haste.

  4. extremely accurate: Annie Oakley was a deadly shot.

  1. in a manner resembling or suggesting death: deadly pale.

  2. excessively;completely: deadly dull.

Origin of deadly

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

synonym study For deadly

1. See fatal.

Other words for deadly

Other words from deadly

  • dead·li·ness, noun
  • non·dead·ly, adjective

Words that may be confused with deadly

Words Nearby deadly Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use deadly in a sentence

British Dictionary definitions for deadly


/ (ˈdɛdlɪ) /

adjective-lier or -liest
  1. likely to cause death: deadly poison; deadly combat

  2. informal extremely boring

adverb, adjective
  1. like death in appearance or certainty: deadly pale; a deadly sleep

Derived forms of deadly

  • deadliness, noun

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012