noun (n)

• a message (spoken or written) that is introduced or inserted(noun.communication)

  Example:
  With the help of his friend's interpolations his story was eventually told.
  

  Synonym:
  insertion
  

  source: wordnet30
• (mathematics) calculation of the value of a function between the values already known(noun.cognition)

  source: wordnet30
• the action of interjecting or interposing an action or remark that interrupts(noun.act)

  Synonym:
  interjection, interpellation, interposition
  

  source: wordnet30
• The act of introducing or inserting anything, especially that which is spurious or foreign.(noun)

  source: webster1913