βίβασις
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)
εως, ἡ,
A a Spartan dance, Poll.4.102. II = ὀχεία, Gloss. III = κοίτη, στιβάς, Hsch.
German (Pape)
[Seite 444] ἡ, Gang, Tanz, Poll. 4, 102; das Bespringenlassen, Sp.