adoptive mother vs matriarch

adoptive mother

noun
  • A woman who has adopted a child, as opposed to a biological mother. 

matriarch

noun
  • The dominant female in a family group of elephants 

  • A female founder of a political or religious movement, an organization or an enterprise. 

  • A female leader of a family, a tribe or an ethnic or religious group. 

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