Source : Webster's Revised Unabridged Dictionary (1913)

Tweed \Tweed\, n. [Probably a corruption of twills. See
   {Twill}.]
   A soft and flexible fabric for men's wear, made wholly of
   wool except in some inferior kinds, the wool being dyed,
   usually in two colors, before weaving.

Source : WordNet®

tweed
     n 1: thick woolen fabric used for clothing; originated in
          Scotland
     2: (usually in the plural) trousers [syn: {flannel}, {gabardine},
         {white}]