[ lee-thuh l ]
/ ˈli θəl /


of, relating to, or causing death; deadly; fatal: a lethal weapon; a lethal dose.
made or carried out to cause death: a lethal chamber; a lethal attack.
causing great harm or destruction: The disclosures were lethal to his candidacy.

Origin of lethal

1575–85; < Latin lētālis, equivalent to lēt(um) death + -ālis -al1; spelling (hence pronunciation) with -h- by association with Greek lḗthē oblivion

Related forms

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for lethality

British Dictionary definitions for lethality


/ (ˈliːθəl) /


able to cause or causing death
of or suggestive of death

Derived Forms

lethality (liːˈθælɪtɪ), nounlethally, adverb

Word Origin for lethal

C16: from Latin lēthālis, from lētum death
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

Medicine definitions for lethality


[ lēthəl ]


Capable of causing death.
Of, relating to, or causing death.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.