adverb (r)

• extremely(adv.all)

  Example:
  Infernally clever.
  

  Synonym:
  all-fired, bloody, boiling, damn, drop-dead, enormously, extraordinarily, goddam, goddamn, goddamned, hellishly, hugely, inordinately, positively, precious, preciously, roaring
  

  source: wordnet30
• In an infernal manner; diabolically.(adverb)

  source: webster1913