fiendish Meaning, Definition & Usage
- 
       adjective satellite extremely evil or cruel; expressive of cruelty or befitting hell
       
       
satanic; infernal; demonic; hellish; unholy; diabolical; diabolic.
- something demonic in him--something that could be cruel
 - fires lit up a diabolic scene
 - diabolical sorcerers under the influence of devils
 - a fiendish despot
 - hellish torture
 - infernal instruments of war
 - satanic cruelty
 - unholy grimaces
 
 
WordNet
Fiend"ish adjective
Definitions
Like a fiend; diabolically wicked or cruel; infernal; malignant; devilish; hellish. --Fiend"ish*ly , adv. --Fiend"ish*ness , n.