diabolical

adjective

UK/ˌdaɪ.əˈbɒl.ɪ.kᵊl/

US/ˌdaɪ.əˈbɑː.lɪ.kᵊl/

Definitions of diabolical adjective

informal
Extremely bad; shockingly poor or unpleasant.
- The service at this restaurant is diabolical.
- I had a diabolical night's sleep last night.
- The team's performance was diabolical.
Related to or characteristic of the Devil; extremely evil.
- He devised a diabolical plot.
- The villain's actions were truly diabolical.
- She had a diabolical smile.