adverb (r)

• to a moderately sufficient extent or degree(adv.all)

  Example:
  He is fairly clever with computers.
  

  Synonym:
  jolly, middling, moderately, passably, pretty, reasonably, somewhat
  Antonym:
  immoderately, unreasonably
  

  source: wordnet30
• without favoring one party, in a fair evenhanded manner(adv.all)

  Example:
  Deal fairly with one another.
  

  Synonym:
  evenhandedly, fair
  

  source: wordnet30
• in conformity with the rules or laws and without fraud or cheating(adv.all)

  Example:
  They played fairly.
  

  Synonym:
  clean, fair
  Antonym:
  below the belt, unfairly
  

  source: wordnet30
• In a fair manner; clearly; openly; plainly; fully; distinctly; frankly.(adverb)

  source: webster1913