in ‧ fer ‧ nal /ɪnˈfɜːnl $ -ɜːr-/ BrE AmE adjective
[ Date: 1300-1400 ; Language: Old French ; Origin: Late Latin infernalis , from infernus 'hell' ]
1 . [only before noun] old-fashioned used to express anger or annoyance about something:
I wish the children would stop that infernal noise.
2 . literary relating to ↑ hell and evil ⇨ hell
—infernally adverb