fa ‧ tal /ˈfeɪtl/ BrE AmE adjective
[ Date: 1300-1400 ; Language: French ; Origin: Latin fatalis , from fatum ; ⇨ ↑ fate ]
1 . resulting in someone’s death:
potentially fatal diseases
fatal accident/illness/injury etc
a fatal climbing accident
If it is not treated correctly, the condition can prove fatal (=be fatal) .
2 . having a very bad effect, especially making someone fail or stop what they are doing
fatal to
Disunity finally proved fatal to the rebels’ cause.
There was one fatal flaw (=serious weakness) in his argument.
His presidential hopes suffered a fatal blow in New Hampshire.
fatal mistake/error
Telling your employees they’re unimportant is a fatal error.