Mother vs mammy

Mother

name
  • A title given to a nun or a priestess. 

  • One of the triune goddesses of the Lady in Wicca alongside the Crone and Maiden and representing a woman older than a girlish Maiden but younger than an aged Crone. 

  • A title given to the personification of a force of nature or abstract concept, such as Mother Nature, Mother Russia, or Mother Earth. 

mammy

noun
  • mamma; mother 

  • In the southern United States, a black nanny employed to look after white children; or in the antebellum South, a female slave who was close to the household and looked after the children. 

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