adverb (r)

• with low volume(adv.all)

  Example:
  Speak softly but carry a big stick.
  The radio was playing softly.
  

  Synonym:
  quietly
  Antonym:
  aloud, loud, loudly
  

  source: wordnet30
• in a manner that is pleasing to the senses(adv.all)

  Example:
  She smiled softly.
  

  source: wordnet30
• with little weight or force(adv.all)

  Synonym:
  gently, lightly
  

  source: wordnet30
• used as a direction in music; to be played relatively softly(adv.all)

  Synonym:
  piano
  Antonym:
  forte, loudly
  

  source: wordnet30
• In a soft manner.(adverb)

  source: webster1913