stepgrandmother (plural stepgrandmothers)
- The stepmother of one's father or mother and the wife of one's grandfather, usually a woman that one's grandfather marries after death of one's grandmother.
- The mother of one's stepmother or stepfather.
2009, January 21, “Jodi Kantor”, in In First Family, a Nation’s Many Faces:
- The president’s elderly stepgrandmother brought him an oxtail fly whisk, a mark of power at home in Kenya.
stepmother of one's parent and wife of one's grandfather