ἀξιοπίστως
From LSJ
Πυλάδη, σε γὰρ δὴ πρῶτον ἀνθρώπων ἐγὼ πιστὸν νομίζω καὶ φίλον ξένον τ' ἐμοί → Pylades for indeed I consider you, foremost among men, loyal and kind and a host to me (Euripides' Electra 82-83)
Russian (Dvoretsky)
ἀξιοπίστως:
1 достоверно, надежно (συνῶπται Arst.);
2 с кажущимся правдоподобием (ψεύδεσθαι Polyb.).