adverb (r)

• one by one; one at a time(adv.all)

  Example:
  They were arranged singly.
  

  Antonym:
  multiply
  

  source: wordnet30
• apart from others(adv.all)

  Example:
  The fine points are treated singly.
  

  Synonym:
  independently, individually, on an individual basis, one by one, separately, severally, severally
  

  source: wordnet30
• Individually; particularly; severally; as, to make men singly and personally good.(adverb)

  source: webster1913