Antonyms of adj fiendish

1 sense of fiendish

Sense 1
demonic, diabolic, diabolical, fiendish, hellish, infernal, satanic, unholy -- (extremely evil or cruel; expressive of cruelty or befitting hell; "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")

INDIRECT (VIA evil) -> good -- (morally admirable)

Similarity of adj fiendish

1 sense of fiendish

Sense 1
demonic, diabolic, diabolical, fiendish, hellish, infernal, satanic, unholy -- (extremely evil or cruel; expressive of cruelty or befitting hell; "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")
       => evil (vs. good) -- (morally bad or wrong; "evil purposes"; "an evil influence"; "evil deeds")