adverb (r)

• in an essential manner(adv.all)

  Example:
  Such expenses are necessarily incurred.
  

  Synonym:
  needfully
  Antonym:
  unnecessarily
  

  source: wordnet30
• in such a manner as could not be otherwise(adv.all)

  Example:
  It is necessarily so.
  

  Synonym:
  inevitably, needs, of necessity
  

  source: wordnet30
• as a highly likely consequence(adv.all)

  Example:
  We are necessarily bound for federalism in Europe.
  

  source: wordnet30
• In a necessary manner; by necessity; unavoidably; indispensably.(adverb)

  source: webster1913