περιτείχισις
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 walling round so as to blockade, circumvallation, Th.2.77, 4.131; but also for defence, π. τοῦ ἄστεος Themist.Ep.4.3.
German (Pape)
[Seite 596] ἡ, das Ummauern, Belagern durch eine Mauer, Thuc. 2, 77. 4, 131 u. Sp.