Definition of "norm"

noun:
- That which is regarded as normal or typical.
  
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- A rule that is enforced by members of a community.
  
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- A sentence with non-descriptive meaning, such as a command, permission, or prohibition.
  
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- A function, generally denoted or , that maps vectors to non-negative scalars and has the following properties:.
  
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verb:
- To endow (a vector space, etc) with a norm.
  
  from Wiktionary, Creative Commons Attribution/Share-Alike License