Simple Definition of fiendish
: very evil or cruel
: extremely bad, unpleasant, or difficult
Full Definition of fiendish
1 : perversely diabolical <took a fiendish pleasure in hurting people>
2 : extremely cruel or wicked
3 : excessively bad, unpleasant, or difficult <fiendish weather>
Examples of fiendish
He takes a fiendish delight in hurting people.
<a fiendish delight in playing cruel tricks>
First Known Use of fiendish
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