δυσκαταπολέμητος
From LSJ
ψυχῆς πείρατα ἰὼν οὐκ ἂν ἐξεύροιο πᾶσαν ἐπιπορευόμενος ὁδόν· οὕτω βαθὺν λόγον ἔχει → one would never discover the limits of soul, should one traverse every road—so deep a measure does it possess
English (LSJ)
ον,
A hard to conquer, D.S.2.48.
German (Pape)
[Seite 682] schwer zu bekämpfen, D. Sic. 2, 48.
Greek (Liddell-Scott)
δυσκαταπολέμητος: -ον, δυσκατανίκητος, Διόδ. 2. 48.