adjective fa·tal \ ˈfā-tᵊl \
|Updated on: 6 Aug 2018

Definition of fatal

1 obsolete : fated
2 : fateful
  • a fatal hour
3 a : of or relating to fate
  • … this science sets a fatal necessity on things …
  • —H. O. Taylor
b : resembling fate in proceeding according to a fixed sequence
c : determining one's fate
  • the fatal flaw in this dazzling woman: a total lack of taste
  • —Marya Mannes
4 a : causing death
  • a fatal crash
  • a fatal disease
  • a fatal wound
b : bringing ruin
  • a fatal attraction to gambling
c : causing failure
  • a fatal design flaw
  • Lack of sufficient support was fatal to his campaign.

Examples of fatal in a Sentence

  1. a disease that is often fatal

  2. a chemical that can be fatal to birds

  3. She made a fatal mistake.

Recent Examples of fatal from the Web

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'fatal.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of fatal

Middle English, from Latin fatalis, from fatum fate

Synonym Discussion of fatal

deadly, mortal, fatal, lethal mean causing or capable of causing death. deadly applies to an established or very likely cause of death.
    • a deadly disease
mortal implies that death has occurred or is inevitable.
    • a mortal wound
fatal stresses the inevitability of what has in fact resulted in death or destruction.
    • fatal consequences
lethal applies to something that is bound to cause death or exists for the destruction of life.
    • lethal gas

FATAL Defined for English Language Learners


Definition of fatal for English Language Learners

  • : causing death

  • : causing ruin or failure

FATAL Defined for Kids


adjective fa·tal \ ˈfā-tᵊl \

Definition of fatal for Students

1 : causing death : mortal
  • fatal injuries
2 : causing ruin or failure
  • a fatal mistake



Medical Dictionary


adjective fa·tal \ ˈfāt-ᵊl \

medical Definition of fatal

: causing death
  • a fatal diabetic coma
  • —Havelock Ellis


play \ˈfāt-ᵊl-ē\ adverb

Law Dictionary


adjective fa·tal

legal Definition of fatal

1 : causing failure of a legal claim or cause of action
  • a fatal defect in the proceedings
  • —W. R. LaFave and J. H. Israel
2 : making something (as a contract) invalid or unenforceable
  • there is a fatal indefiniteness with the result that the agreement is void
  • —J. D. Calamari and J. M. Perillo



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