1. Showing the cunning or ingenuity or wickedness typical of a devil
   "the diabolical expression on his face"
   - devilish, diabolic, mephistophelian, mephistophelean 
2. Extremely evil or cruel; expressive of cruelty or befitting hell
   "diabolical sorcerers under the influence of devils"
   - demonic, diabolic, fiendish, hellish, infernal, satanic, unholy

See also: evil

• fistulous
• fistulous withers
• fit
• fit in
• fit out
• fit the bill
• fitch
• fitchew
• fitful
• fitfully
• fitfulness
• fitly
• fitment
• fitness
• fits and starts
• fitted
• fitted out
• fitted sheet
• fitter
• fitting
• fittingly
• fittingness
• Fitzgerald
• five
• five dollar bill