Entry 1 sense Webster, 1913 Hellish /hĕl'-ĭsh/ · Hell·ish · IPA /ˈhɛlɪʃ/ 01 a. Of or pertaining to hell; like hell; infernal; malignant; wicked; detestable; diabolical. 1. Of or pertaining to hell; like hell; infernal; malignant; wicked; detestable; diabolical.