trews

from WordNet (r) 3.0 (2006)

trews
    n 1: tight-fitting trousers; usually of tartan

from The Collaborative International Dictionary of English v.0.48

Trews \Trews\, n. pl.
   Trowsers; especially, those of the Scotch Highlanders. "He
   wore the trews, or close trowsers, made of tartan." --Sir W.
   Scott.
   [1913 Webster]