1. showing the cunning or ingenuity or wickedness typical of a devil;
"devilish schemes""the cold calculation and diabolic art of some statesmen""the diabolical expression on his face""a mephistophelian glint in his eye"
2. extremely evil or cruel; expressive of cruelty or befitting hell;
"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"