HELLISH
demonic, diabolic, diabolical, fiendish, hellish, infernal, satanic, unholy
(adjective) 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”
beastly, hellish, god-awful
(adjective) (informal) very unpleasant; “hellish weather”; “stop that god-awful racket”
Source: WordNet® 3.1
Etymology
Adjective
hellish (comparative more hellish, superlative most hellish)
Causing pain, discomfort or distress.
Synonyms
• awful
• horrible
• terrible
• nightmarish
• infernal
Antonyms
• heavenly
Source: Wiktionary
Hell"ish, a.
Definition: Of or pertaining to hell; like hell; infernal; malignant;
wicked; detestable; diabolical. "Hellish hate." Milton.
– Hell"ish*ly, adv.
– Hell"ish*ness, n.
Source: Webster’s Unabridged Dictionary 1913 Edition