As adjectives the difference between unyielding and fiendish
is that unyielding is not giving in; not bending; stubborn while fiendish is sinister; evil; conniving; in the manner of a fiend.
fiendish
English
Adjective
(
en adjective)
Sinister; evil; conniving; in the manner of a fiend.
Derived terms
* fiendishly
* fiendishness
Anagrams
* finished