Definition of "posh"

adjective:
- Associated with the upper classes.
  
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- Stylish, elegant, exclusive (expensive).
  
  from Wiktionary, Creative Commons Attribution/Share-Alike License
- Snobbish, materialistic, prejudiced, under the illusion that they are better than everyone else. usually offensive. (especially in Scotland and Northern England).
  
  from Wiktionary, Creative Commons Attribution/Share-Alike License
interjection:
- An exclamation expressing derision.
  
  from Wiktionary, Creative Commons Attribution/Share-Alike License