1. (Of a disease) Having a rapid course and violent effect.
2. (Theology) Involving loss of divine grace or spiritual death; SYN. mortal.
3. Causing or capable of causing death; SYN. deathly, mortal.
4. Extremely poisonous or injurious; producing venom; SYN. venomous, virulent.
5. Of an instrument of certain death; SYN. lethal.
(Familier) Ennuyeux.