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See more synonyms for deadly on Thesaurus.com
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.
  3. like death: a deadly pallor.
  4. excruciatingly boring: The dinner party was absolutely deadly.
  5. excessive; inordinate: deadly haste.
  6. extremely accurate: Annie Oakley was a deadly shot.
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  1. in a manner resembling or suggesting death: deadly pale.
  2. excessively; completely: deadly dull.
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Origin of deadly

before 900; Middle English deedli(ch), Old English dēadlīce. See dead, -ly
Related formsdead·li·ness, nounnon·dead·ly, adjective
Can be confuseddeadly deathly


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1. See fatal. 4. dull, tedious, tiresome.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words


Examples from the Web for deadliest

Contemporary Examples

Historical Examples

  • After all, I was her only boy, and it was to war in its deadliest form that I was going.

    In the Valley

    Harold Frederic

  • In an Italian town he is always at work, and always thumping in the deadliest manner.

  • Look at the tastes and habits of our age—the deadliest enemies of true religion!

    The Christian

    Hall Caine

  • If the cloud were no bigger than a man's hand, it was charged with deadliest lightning.

    Gerald Fitzgerald

    Charles James Lever

  • Could settle the deadliest quarrel in the country by crooking his little finger.

    Lord Jim

    Joseph Conrad

British Dictionary definitions for deadliest


adjective -lier or -liest
  1. likely to cause deathdeadly poison; deadly combat
  2. informal extremely boring
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adverb, adjective
  1. like death in appearance or certaintydeadly pale; a deadly sleep
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Derived Formsdeadliness, 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

Word Origin and History for deadliest



Old English deadlic "mortal, subject to death," also "causing death;" see dead + -ly (1). Meaning "having the capacity to kill" is from late 14c. (Old English words for this included deaðbærlic, deaðberende).

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Online Etymology Dictionary, © 2010 Douglas Harper