deadly

(of a disease) having a rapid course and violent effect

causing or capable of causing death

a fatal accident

a deadly enemy

of an instrument of certain death

deadly poisons

lethal weapon

exceedingly harmful

involving loss of divine grace or spiritual death

the seven deadly sins

extremely poisonous or injurious; producing venom

venomous snakes

a virulent insect bite

(used as intensives) extremely

she was madly in love

deadly dull

as if dead