noun (n)

• the act of sharing in the activities of a group(noun.act)

  Synonym:
  engagement, involution, involvement
  Antonym:
  non-engagement, non-involvement, nonparticipation
  

  source: wordnet30
• the condition of sharing in common with others (as fellows or partners etc.)(noun.state)

  Synonym:
  involvement
  

  source: wordnet30
• The act or state of participating, or sharing in common with others; as, a participation in joy or sorrows.(noun)

  source: webster1913