The Collaborative International Dictionary of English v.0.48:

Serge \Serge\, n. [F. serge, sarge, originally, a silken stuff,
   fr. L. serica, f. or neut. pl. of sericus silken. See
   Sericeous, Silk.]
   A woolen twilled stuff, much used as material for clothing
   for both sexes.
   [1913 Webster]

   Silk serge, a twilled silk fabric used mostly by tailors
      for lining parts of gentlemen's coats.
      [1913 Webster]