Lewis & Short

praecinctĭo, ōnis, f. [praecingo], lit.,

  1. I. a girding about, a girdle: zonae, Hilar. in Matt. 2, 2.
    Hence,
  2. II. Transf., the broad landing-place or lobby around the amphitheatre, or between each tier of seats, Vitr. 5, 3; 2, 8.