fiendish
Like a demon
Fiendish means diabolically cruel or wicked, like a fiend—a demon or devil.
A fiendish plot suggests malicious cunning; a fiendish grin hints at sadistic pleasure.
The word also describes extreme difficulty or complexity: a fiendish puzzle, fiendish calculus problems.
Both senses share the quality of being devilishly challenging to endure or overcome.
Extremely wicked or cruel
- satanicExtremely wicked or cruel
- infernalOf the underworld
- hellishExtremely unpleasant or cruel
- demonicOf or like devils
devilish · unholy · accursed · sinister · nefarious · villainous · evil · malevolent
Hard to accomplish
- perplexingCausing mental confusion
- bafflingImpossible to understand
- maddeningCausing extreme frustration
- vexingCausing mild torment
torturous · devilish · punishing · grueling · brain-teaser · puzzle · conundrum · riddle
Cleverly original in design
- masterlyShowing superior skill
- brilliantIntensely bright or gifted
- intricateElaborately detailed, many parts
- elaborateComplex and detailed
sophisticated · complex · inventive · cunning · crafty · artful · byzantine · labyrinthine
Savagely harsh or severe
- mercilessShowing no clemency
- savageFierce and untamed
- viciousCruelly aggressive in nature
- sadisticFinding pleasure in cruelty
heartless · callous · ruthless · pitiless · inhuman · inhumane · barbaric · cold-blooded
Sly, scheming cleverness
- schemingCrafty and calculating
- craftyCleverly deceptive
- slyCleverly deceptive
- manipulativeSkilled at controlling others
conniving · calculating · underhanded · insidious · treacherous · sneaky · deceitful · duplicitous
diabolical
Extremely wicked or cruel
demonic · devilish · unholy · accursed · sinister · nefarious · villainous · evil · malevolent · ghoulish
challenging
Hard to accomplish
- perplexingCausing mental confusion
- bafflingImpossible to understand
- maddeningCausing extreme frustration
vexing · torturous · devilish · punishing · grueling · brain-teaser · puzzle · conundrum · riddle · cryptic
ingenious
Cleverly original in design
- masterlyShowing superior skill
- brilliantIntensely bright or gifted
- intricateElaborately detailed, many parts
elaborate · sophisticated · complex · inventive · cunning · crafty · artful · byzantine · labyrinthine
brutal
Savagely harsh or severe
sadistic · heartless · callous · ruthless · pitiless · inhuman · inhumane · barbaric · cold-blooded · monstrous
cunning
Sly, scheming cleverness
manipulative · conniving · calculating · underhanded · insidious · treacherous · sneaky · deceitful · duplicitous · guileful
- wickedevil, wicked, villainous, malicious, sinister
- infernalhellish, demonic, diabolical, satanic, devilish
- scary feelingsterrified, frightening, dreadful, creepiness, goosebumps
- SatanSatan, devil, Lucifer, Beelzebub, Mephistopheles
fiendishsimple
Free of complexity
straightforward · easy · uncomplicated · elementary · effortless
fiendishbenevolent
Desiring others' welfare
merciful · compassionate · kind · kindhearted · benign