mammy vs mummy

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. 

mummy

noun
  • mother. 

  • Any naturally preserved human or animal body. 

  • An embalmed human or animal corpse wrapped in linen bandages for burial, especially as practised by the ancient Egyptians and some Native American tribes. 

  • A reanimated embalmed human corpse, as a stock character in horror films. 

  • A substance used in medicine, prepared from mummified flesh. 

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