step-grandmother

Noun

stepgrandmother (plural stepgrandmothers)

1. The stepmother of one's father or mother and the wife of one's grandfather, usually a woman that one's grandfather marries after the divorce of one's grandparents or the death of one's grandmother.
2. The mother of one's stepmother or stepfather.
   • The president’s elderly stepgrandmother brought him an oxtail fly whisk, a mark of power at home in Kenya.2009 January 21, Jodi Kantor, “In First Family, a Nation’s Many Faces”, in New York Times