As adjectives the difference between diabolical and fiendish
is that diabolical is extremely wicked or cruel while fiendish is sinister; evil; conniving; in the manner of a fiend.
diabolical
English
Adjective
(
en adjective)
Extremely wicked or cruel.
Of or concerning the devil; satanic.
Derived terms
* diabolically
* diabolicalness
Related terms
* diabolic
References
fiendish
English
Adjective
(
en adjective)
Sinister; evil; conniving; in the manner of a fiend.
Derived terms
* fiendishly
* fiendishness
Anagrams
* finished