The Collaborative International Dictionary of English v.0.48:

Modiste \Mo`diste"\, n. [F. See Mode; cf. Modist.]
   One, esp. a woman, who makes, or deals in, articles of
   fashion, esp. of the fashionable dress of ladies; a
   dress-maker or milliner.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

modiste
    n 1: someone who makes and sells hats [syn: hatmaker,
         hatter, milliner, modiste]
    2: someone who makes or mends dresses [syn: dressmaker,
       modiste, needlewoman, seamstress, sempstress]