διαγώνισις

From LSJ

μηδενί δίκην δικάσῃς πρίν ἀμφοῖν μῦθον ἀκούσῃς → do not give your judgement on anything until you have heard a speech on both sides

Source

Spanish (DGE)

-εως, ἡ competición glos. a ἀγών Sch.Er.Il.24.1b.