deadly

adj

1.
causing or capable of causing death
Derived from:
deadliness
2.
of an instrument of certain death
Derived from:
deadliness
3.
extremely poisonous or injurious; producing venom
Derived from:
deadliness
4.
involving loss of divine grace or spiritual death
Derived from:
deadliness
5.
exceedingly harmful
Derived from:
deadliness
6.
(of a disease) having a rapid course and violent effect
Derived from:
deadliness