βοήθεια
From LSJ
αὐτὸν κέκρουκας τὸν βατῆρα τοῦ λόγου → you have struck the very threshold of the argument, you have struck the most important and chiefmost point
English (LSJ)
ἡ (Dor. βοάθοια SIG421.36 (Thermon)),
A help, aid, Th.2.22, etc.; β. τῷ λόγῳ πρός τινα Pl.Prm. 128c; ἡ ὑπὲρ τῶν δικαίων β. D.56.15; βοήθειαν ἔχειν πρὸς ὑγίειαν, πρὸς τὴν ἑκάστου ὑπερβολὴν μηχανᾶσθαι, Arist.PA651b1, 652a32: nom.sg., as exclamation 'help!', Plb.13.8.5: pl., Gorg.Pal.33, D.18.302, Arist. Rh.1383a29; αἱ πρὸς εὔπλοιαν β. Ph.2.46, cf. Act.Ap.27.17. 2 medical aid, cure, κίνδυνος ἰσχυρότερος πάσης β. Plu.Alex.19. II force of auxiliaries, ἡ παρὰ Διονυσίου β. X.HG7.1.20; νεῶν β. Th.4.8: opp. regular forces, D.4.32.