προπένθερος
From LSJ
εἰ ἔρρωσαι καὶ ἐν τοῖς ἄλλοις ἀλύπως ἀπαλλάσσεις → if you are well and in other respects are getting on without annoyance
English (LSJ)
ὁ, one's father-in-law's father, Sch.rec.S.OT1494.
German (Pape)
[Seite 739] ὁ, Großschwiegvater, Sp., wie Schol. Soph. O. R. 1508.
Greek (Liddell-Scott)
προπένθερος: ὁ πατὴρ τοῦ πενθεροῦ, μνημονεύεται ἐκ τῶν Σχολ. εἰς Σοφ.