1. 魔鬼（似）的;恶魔（般）的;邪恶的
Demonic means coming from or belonging to a demon or being like a demon.

2. (精力、决心、能力等)超乎常人的
If someone has demonic energy, drive, or abilities, they are more energetic, determined, or clever than most people.

1. extremely evil or cruel
expressive of cruelty or befitting hell

e.g. something demonic in him--something that could be cruel
fires lit up a diabolic scene
diabolical sorcerers under the influence of devils
a fiendish despot
hellish torture
infernal instruments of war
satanic cruelty
unholy grimaces

Synonym: diabolicdiabolicalfiendishhellishinfernalsatanicunholy