Lewis & Short

praetentūra, ae, f. [praetendo],

  1. I. a military guard on the boundaries of a province, a frontier-guard (post-class.): Mesopotamiae tractus praetenturis et stationibus servabantur agrariis, Amm. 14, 3, 2.
  2. II. A barricade, Amm. 14, 2, 4.