hellish vs diabolical

hellish and diabolical both are adjectives.

Word	Noun	Adjective	Verb	Adverb
hellish	No	Yes	No	No
diabolical	No	Yes	No	No

As adjectives, hellish and diabolical are synonyms defined as:

hellish and diabolical: extremely evil or cruel; expressive of cruelty or befitting hell

Other synonyms of hellish include demonic, diabolic, fiendish, infernal, satanic, unholy.

hellish (adjective)	diabolical (adjective)
extremely evil or cruel; expressive of cruelty or befitting hell	extremely evil or cruel; expressive of cruelty or befitting hell
(informal) very unpleasant	showing the cunning or ingenuity or wickedness typical of a devil