noun (n)

• the act of making or doing something in return(noun.act)

  source: wordnet30
• alternating back-and-forth movement(noun.act)

  source: wordnet30
• mutual interaction; the activity of reciprocating or exchanging (especially information)(noun.act)

  Synonym:
  give-and-take, interchange
  

  source: wordnet30
• The act of reciprocating; interchange of acts; a mutual giving and returning; as, the reciprocation of kindnesses.(noun)

  source: webster1913