idiom vs patois

idiom

noun
  • A language or language variety; specifically, a restricted dialect used in a given historical period, context etc. 

  • An artistic style (for example, in art, architecture, or music); an instance of such a style. 

  • A manner of speaking, a mode of expression peculiar to a language, language family, or group of people. 

  • An established phrasal expression whose meaning may not be deducible from the literal meanings of its component words. 

  • A programming construct or phraseology that is characteristic of the language. 

patois

noun
  • A regional dialect of a language (especially French); usually considered substandard. 

  • Jamaican Patois, a Jamaican creole language primarily based on English and African languages but also has influences from Spanish, Portuguese and Hindi. 

  • Jargon or cant. 

  • Creole French in the Caribbean (especially in Dominica, St. Lucia, Trinidad and Tobago and Haiti). 

  • Any of various French or Occitan dialects spoken in France. 

How often have the words idiom and patois occurred in a corpus of books? (source: Google Ngram Viewer )