ἐρυμνότης
From LSJ
εἰργάζοντο λογάδην φέροντες λίθους καὶ ξυνετίθεσαν ὡς ἕκαστόν τι ξυμβαίνοι → they went to work bringing the stones as they picked them out and put them together as each one happened to fit
English (LSJ)
ητος, ἡ,
A strength or security of a place, X.Cyr.6.1.23 ; τῶν τειχῶν Arist.Pol.1330b37 ; αἱ ἐ. τῶν Ἄλπεων the difficulties of passing them, Plb.3.47.9, etc.