ἄφρακτος
From LSJ
ἀγεωμέτρητος μηδεὶς εἰσίτω → no one ignorant of geometry may enter, let no one ignorant of geometry enter, let no one ignorant of geometry come in
English (LSJ)
ον, old Att. ἄφαρκτος (though this form has generally been altered by the copyists),
A unfenced, unfortified, unguarded, οἴκησις, στρατόπεδον, Th.1.6,117: c. gen., ἀ. φίλων by friends, S.Aj.910 (lyr.); of ships, not decked, IG12(1).44 (Rhodes); of horses, opp. πεφραγμένοι, Arr.Tact.2.5. 2 not obstructed, Gal.17(1).598. 3 not to be kept in, irrepressible, σταγόνες A.Ch.186 (with v.l. ἄφραστοι). II unguarded, off one's guard, ᾑρέθην E.Hipp.657; ληφθήσεσθε Th.6.33, cf. Ar.Th.581; πρός τινα Th.3.39.
