fiendish
1. [ adjective ] extremely evil or cruel; expressive of cruelty or befitting hell
Synonyms: infernal unholy satanic hellish diabolic diabolical demonic
Examples:

"something demonic in him" "fires lit up a diabolic scene" "a fiendish despot" "hellish torture" "infernal instruments of war" "satanic cruelty" "unholy grimaces"

Related terms: evil
Similar spelling:   fiendishly