noun (n)

• a standard or model or pattern regarded as typical(noun.linkdef)

  Example:
  The current middle-class norm of two children per family.
  

  source: wordnet30
• a statistic describing the location of a distribution(noun.cognition)

  Example:
  It set the norm for American homes.
  

  Synonym:
  average
  

  source: wordnet30
• A rule or authoritative standard; a model; a type.(noun)

  source: webster1913