fiendish

adjective fiend·ish \ˈfēn-dish\

: very evil or cruel

: extremely bad, unpleasant, or difficult

Full Definition of FIENDISH

: perversely diabolical <took a fiendish pleasure in hurting people>

: extremely cruel or wicked

: excessively bad, unpleasant, or difficult <fiendish weather>

— fiend·ish·ly adverb

— fiend·ish·ness noun

See fiendish defined for English-language learners

1529

Synonyms: cacodemonic, demoniac (also demoniacal), demonian, demonic (also demonical), devilish, diabolical (or diabolic), Luciferian, satanic

Next Word in the Dictionary: fiendlyPrevious Word in the Dictionary: fiendAll Words Near: fiendish

What made you want to look up fiendish? Please tell us where you read or heard it (including the quote, if possible).

Put-downs with flair

How to use a word that (literally) drives some people nuts.

Test your vocab with our fun, fast game

Ailurophobia, and 9 other unusual fears