/ ˈfeɪtl; NAmE / adjective
1.
causing or ending in death :
a fatal accident / blow / illness
a potentially fatal form of cancer
If she gets ill again it could prove fatal .
—compare mortal
2.
causing disaster or failure :
a fatal error / mistake
Any delay would be fatal.
There was a fatal flaw in the plan.
It'd be fatal to try and stop them now.
► fa·tal·ly / -təli; NAmE / adverb :
fatally injured / wounded
The plan was fatally flawed from the start.
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WORD ORIGIN
late Middle English (in the senses destined by fate and ominous ): from Old French , or from Latin fatalis , from fatum that which has been spoken, from fari speak.