- of or like a fiend
- diabolically wicked or cruel
- informal extremely difficult or unpleasant
WordReference Random House Unabridged Dictionary of American English © 2026
fiend•ish
(fēn′dish),USA pronunciation adj.
fiend′ish•ly, adv.
fiend′ish•ness. n.
- diabolically cruel and wicked.
- fiend + -ish1 1520–30
fiend′ish•ness. n.
Collins Concise English Dictionary © HarperCollins Publishers::
fiendish /ˈfiːndɪʃ/ adj
fiend /find/USA pronunciation
n. [countable]
fiend•ish•ly, adv.
WordReference Random House Unabridged Dictionary of American English © 2026- any evil spirit;
demon. - an extremely cruel or wicked person.
- Informal Termsa person who is addicted or very attached to some habit, practice, condition, etc.:a fiend for neatness.
fiend•ish•ly, adv.
fiend
(fēnd),USA pronunciation n.
fiend′like′, adj.
- Satan;
the devil. - any evil spirit;
demon. - a diabolically cruel or wicked person.
- a person or thing that causes mischief or annoyance:Those children are little fiends.
- Informal Termsa person who is extremely addicted to some pernicious habit:an opium fiend.
- Informal Termsa person who is excessively interested in some game, sport, etc.;
fan;
buff:a bridge fiend. - a person who is highly skilled or gifted in something:a fiend at languages.
- bef. 900; Middle English feend, Old English fēond; cognate with German Feind, Old Norse fjandr, Gothic fijands foe, origin, originally present participle of fijan to hate
- 3. monster, savage, brute, beast, devil.
'fiendish' also found in these entries (note: many are not synonyms or translations):