adverb (r)

• with firmness(adv.all)

  Example:
  `I will come along,' she said decisively.
  

  Synonym:
  firmly, hard, resolutely
  

  source: wordnet30
• with finality; conclusively(adv.all)

  Example:
  The voted settled the argument decisively.
  

  Antonym:
  indecisively
  

  source: wordnet30
• in an indisputable degree(adv.all)

  Example:
  The Fisher Act of 1918 decisively raised their status and pay.
  

  source: wordnet30