US also diabolic [adjective] - extremely bad and shocking(informal) Conditions in the prison were said to be diabolical.(informal) His driving is diabolical!Diabolical also means evil, or caused by the Devil (= in Christianity and Judaism, the originator of evil and the enemy of God).
DIABOLICAL
Meaning of DIABOLICAL in English
Cambridge English vocab. Кембриджский английский словарь. 2012