βῆναι

From LSJ

ἐγγυητής τοῦ ἀργυρίου ἀξιόχρεωςtrustworthy guarantor for the money

Source

French (Bailly abrégé)

inf. ao.2 de βαίνω.

Russian (Dvoretsky)

βῆναι: inf. aor. к βαίνω.