Diabolical (adj)
dai-a-bol-i-kal
Characteristic of the Devil, or so evil as to be suggestive of the Devil.
(British) (informal) Disgracefully bad or unpleasant.
Late Middle English (as diabolic): from Old French diabolique or ecclesiastical Latin diabolicus, from diabolus ‘devil’; the form diabolical dates from the early 16th century.
Example sentences
“He showed a diabolical cunning.”
“His diabolical behaviour drove everyone away.”