adverb (r)

• to a high degree or extent; favorably or with much respect(adv.all)

  Example:
  Extremely interesting.
  

  Synonym:
  highly
  

  source: wordnet30
• to an extreme degree(adv.all)

  Example:
  Extremely cold.
  Extremely unpleasant.
  

  Synonym:
  exceedingly, passing, screamingly, super
  

  source: wordnet30
• In an extreme manner or state; in the utmost degree; to the utmost point; exceedingly; as, extremely hot or cold.(adverb)

  source: webster1913