ἴστωρ · istōr — LSJ
one who knows law and right, judge, witnesses
one who knows law and right, judge, ἐπὶ ἴστορι πεῖραρ ἑλέσθαι Il. 18.501; ἴστορα δʼ Ἀτρείδην Ἀγαμέμνονα θείομεν ἄμφω 23.486; ϝίστορες witnesses, IG 7.1779 (Thespiae); τῶ τεθμίω ϝίστωρ Schwyzer 523.64 (Orchom. Boeot.); θεοὺς πάντας ἵστορας ποιεύμενος Hp. Jusj. 1init., cf. Poll. 8.106.
II knowing, learned, knowing, skilled in
Adj. knowing, learned, Hes. Op. 792; ἵ. τινός knowing a thing, skilled in it, ᾠδῆς h.Hom. 32.2; ἐγχέων B. 8.44; κἀγὼ τοῦδʼ ἴ. ὑπερίστωρ S. El. 850 (lyr), cf. E. IT 1431, Pl. Cra. 406b. (From ϝιδ-τωρ, cf. οἶδα: ἵστωρ acc. to Hdn.Gr. 2.108, etc.)