fatal

adjective
C1+
1
C1+
causing or ending in death
مهلک, کشنده, مرگبار
compare mortal
2
C1+
causing disaster or failure
مهلک, ویرانگر
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.