Source : Webster's Revised Unabridged Dictionary (1913)

Trews \Trews\, n. pl.
   Trowsers; especially, those of the Scotch Highlanders. ``He
   wore the trews, or close trowsers, made of tartan.'' --Sir W.
   Scott.

Source : WordNet®

trews
     n : tight-fitting trousers; usually of tartan