What is the meaning of convention?

noun

• A large formal assembly.
  • usage: "political convention"
• Something regarded as a normative example.
  • usage: "the convention of not naming the main character"; "violence is the rule not the exception"; "his formula for impressing visitors"
  • synonyms: normal, pattern, rule, formula
• Diplomacy) an international agreement. (
• Orthodoxy as a consequence of being conventional.
  • synonyms: conventionality, conventionalism
• The act of convening.
  • synonyms: convening