noun (n)

• an argument that is conclusive(noun.communication)

  Synonym:
  determiner, determining factor
  

  source: wordnet30
• a point or fact or remark that settles something conclusively(noun.cognition)

  Synonym:
  decisive factor
  

  source: wordnet30
• a tool used to clinch nails or bolts or rivets(noun.artifact)

  source: wordnet30
• One who, or that which, clinches; that which holds fast.(noun)

  source: webster1913