in·fer·nal 
/ɪnˈfɚnl̟/ adjective
always used before a noun /ɪnˈfɚnl̟/ adjective 1 literary : of or relating to hell
▪ the infernal regions of the dead 2 informal + old-fashioned : very bad or unpleasant
▪ Stop making that infernal racket! ▪ an infernal nuisance/pest
▪ the infernal regions of the dead
▪ Stop making that infernal racket! ▪ an infernal nuisance/pest
— in·fer·nal·ly /ɪnˈfɚnl̟i/ adverb
▪ an infernally [=extremely] difficult problem
/ɪnˈfɚnl̟i/ adverb ▪ an infernally [=extremely] difficult problem
