noun (n)

• a characteristic language of a particular group (as among thieves)(noun.communication)

  Synonym:
  argot, cant, jargon, lingo, slang, vernacular
  

  source: wordnet30
• a regional dialect of a language (especially French); usually considered substandard(noun.communication)

  source: wordnet30
• A dialect peculiar to the illiterate classes; a provincial form of speech.(noun)

  source: webster1913