mongrelize

/ˈmʌŋɡrəlaɪz/
verb
  1. To cause (a breed, group, or culture) to become mixed in origin or character, often with a negative connotation of impurity.
    • The breeder refused to mongrelize his purebred dogs by crossing them with other breeds.
    • They worried that globalization would mongrelize local languages and customs.
    • Some critics accused the new policies of mongrelizing the traditional culture.
Antonyms