great-great-grandmother
Refers to the mother of one's great-grandparent. A specific kinship term used in formal or genealogical contexts.
My great-great-grandmother was born in the Meiji era.
Compound of 高 (こう, 'great-', indicating a further generation) and 祖母 (そぼ, 'grandmother'). The prefix 高 is used in kinship terms to denote an additional generation beyond 曾 (そう).