Serge's a type of twill fabric that's diagonal lines or ridges on both sides, made with a two-up, two-down weave. The worsted variety's used in making military uniforms, suits, great and trench coats. Its counterpart, silk serge,'s used for linings. French serge's a softer, finer variety. The word's also used for a high quality woolen woven. Etymology and history The name's derived from Old French serge, itself from Latin serica, from Greek σηρικος (serikos)… (More on Serge)