Fiendish is a related term of unmerciful.
As adjectives the difference between fiendish and unmerciful
is that fiendish is sinister; evil; conniving; in the manner of a fiend while unmerciful is not showing mercy.
fiendish
English
Adjective
(
en adjective)
Sinister; evil; conniving; in the manner of a fiend.
Derived terms
* fiendishly
* fiendishness
Anagrams
* finished
unmerciful
English
Synonyms
* merciless
Antonyms
* merciful
See also
* cruel
* inhuman
External links
*
*
*