basilect vs usage

basilect

noun
  • A variety of a language that has diverged greatly from the standard form, and is only considered suitable for very informal contexts by speakers. 

usage

noun
  • The established custom of using language; the ways and contexts in which spoken and written words are used, especially by a certain group of people or in a certain region. 

  • Custom, tradition. 

  • A custom or established practice. 

  • The act of using something; use, employment. 

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