ἄκλονος
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)
ον, of the pulse,
A steady, regular, Gal.9.347; of a limb, free from jars, 17(1).513; of a rider, with a firm seat, Palaeph.52.