Showing wickedness typical of a devil. / Extremely evil or cruel.

Extremely wicked or cruel. / Of or concerning the devil; satanic.

In a diabolical manner.

plural of diabolicality

The state or quality of being diabolical.

(uncountable) Worship of the devil; Satanism / (countable) Character, action, utterances, creative works, behavior or principles appropriate to the devil.

plural of diabolism

simple past tense and past participle of diabolize

Third-person singular simple present indicative form of diabolize

present participle of diabolize