noun (n)

• a requirement of etiquette or custom(noun.event)

  Example:
  A mere formality.
  

  Synonym:
  formalities
  

  source: wordnet30
• a manner that strictly observes all forms and ceremonies(noun.attribute)

  Example:
  The formality of his voice made the others pay him close attention.
  

  Synonym:
  formalness
  Antonym:
  informality
  

  source: wordnet30
• compliance with formal rules(noun.act)

  Example:
  Courtroom formality.
  

  source: wordnet30
• The condition or quality of being formal, strictly ceremonious, precise, etc.(noun)

  source: webster1913