|dīə|bälik, -lēk adjective
or di·a·bol·i·cal -lə̇kəl, -lēk-
Etymology: diabolic from Middle English deabolik, from Middle French diabolique, from Late Latin diabolicus, from diabolus devil + Latin -icus -ic; diabolical from Middle French diabolique + English -al — more at devil
1. : of or relating to the devil or devils
Lucifer is … forced to reassume his diabolic shape — Modern Language Review
diabolic lore
: derived from the devil
diabolic arts
difference between the angelic and the diabolic temperament — G.B.Shaw
: being under the influence of devils
diabolical sorcerers — Herman Melville
: resembling a devil
a diabolic figure
: being a devil
a diabolic visitor
: suggestive of devils or hell
fires lit up a truly diabolic scene
2. : resembling that of devils : befitting or characteristic of a devil typically in having or showing cunning, ingenuity, cruelty, or wickedness : devilish , fiendish
the cold calculation and the diabolic art of these statesmen
his expression changing to something diabolical — Rudyard Kipling
• di·a·bol·i·cal·ly -lə̇k(ə)lē, -lēk-, -li adverb
• di·a·bol·i·cal·ness noun -es