ἀνεξέλεγκτος

1. unquestioned, impossible to be questioned or refuted , of statements or arguments, (Thucydides); ἀν. ἔχει τὸ ἀνδρεῖον leaves their courage without proof , (Thucydides)
2. of persons, not to be convicted, irreproachable , (Xenophon Historicus), etc. (ML)