/ ɪnˈfɜːnəʊ; NAmE ɪnˈfɜːrnoʊ/ noun
[ usually sing. ] ( pl. -os ) a very large dangerous fire that is out of control :
a blazing / raging inferno
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WORD ORIGIN
mid 19th cent.: from Italian , from Christian Latin infernus below, underground, used by Christians to mean hell, on the pattern of inferni (masculine plural) the shades and inferna (neuter plural) the lower regions.