ἀρχιγέρων
From LSJ
τοῖς οἰκείοις βουλεύμασιν ἁλίσκεσθαι → hoist by one's own petard, hoist with one's own petard, hoist on one's own petard, hoisted by one's own petard, be hoist with one's own petard
English (LSJ)
οντος, ὁ,
A chief of a γερουσία, Sammelb.2100 (i B.C.), Cod.Just.1.4.5.
Greek (Liddell-Scott)
ἀρχιγέρων: -οντος, ὁ ὁ πρῶτος τῶν γερόντων, πρόεδρος τῆς γερουσίας, Βυζ.