καθαρτής
From LSJ
ἵνα οὖν μηδ' ἐν τούτῳ δῷ αὐτοῖς λαβήν (Photius, Fragments on the Epistle to the Romans 483.26) → so that he doesn't give them even here a handle (= an opportunity for refutation)
English (LSJ)
οῦ, ὁ,
A cleanser, purifier, μάγοι καὶ κ. Hp.Morb. Sacr.1, cf. D.Chr.4.89(pl.); σοῦ γὰρ ἔρχομαι . . κ. S.El.70; στρατοῦ κ. Id.Fr.34; τῆς χώρας Ar.V.1043; ποταμῶν Plu.Luc.26; θηρίων, of Heracles, Max.Tyr.21.6: metaph., δοξῶν . . . περὶ ψυχὴν κ. εἶναι Pl.Sph. 231e; as occupational name, IG5(1).209.25 (i B.C.).