Lewis & Short

saeptĭo, ōnis, f. [saepio].

  1. I. Prop., a hedging or fencing in, enclosing (post-Aug.), Vitr. 5, 12, 5; 6, 11 (8), 5.
  2. II. Meton., an enclosing with a wall, etc.; with obj. gen.: urbis, the erection of a wall around it, Vop. Aur. 12.