μητρομήτωρ
From LSJ
τούτου δὲ συμβαίνοντος ἀναγκαῖον γίγνεσθαι πάροδον καὶ τροπὰς τῶν ἐνδεδεμένων ἄστρων → but if this were so, there would have to be passings and turnings of the fixed stars
English (LSJ)
Dor. ματρομάτωρ, ορος, ἡ,
A mother's mother, grandmother, Pi.O.6.84, Ael.NA11.16.
German (Pape)
[Seite 180] ορος, ἡ, Mutter der Mutter, Großmutter mütterlicher Seits; Ael. N. A. 11, 16; Pind. Ol. 6, 84, in dor. Form ματρομάτωρ.