1. The mother of one's stepgrandparent.
2. The stepmother of one's grandparent.
My step-great-grandmother is a good person.
by Elivaldeq November 24, 2019
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1. The grandmother of one's stepmother or stepfather.

2.The stepmother of one's grandmother or grandfather.

3.The mother of one's grandmother's husband or grandfather's wife; but not their biological great-grandmother.
His Step Great-Grandmother was the wife of his Great-Grandfather.
by Stepman December 11, 2017
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