Lewis & Short

thĕristrum, i, n., = θέριστρον, a summer garment.

  1. I. Lit. (late Lat.), Hier. in Isa. 2, 3, 23; Vulg. Gen. 38, 14.
  2. II. Trop., a garment, covering: theristrum pudicitiae, Hier. Ep. 107, 7.