The Collaborative International Dictionary of English v.0.48:

Sachet \Sa`chet"\, n. [F., dim. of sac. See Sac.]
   A scent bag, or perfume cushion, to be laid among
   handkerchiefs, garments, etc., to perfume them.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sachet
    n 1: a small soft bag containing perfumed powder; used to
         perfume items in a drawer or chest

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "sachet":
   atomizer, censer, fumigator, incense burner, incensory, odorator,
   odorizer, parfumoir, perfumer, pomander, potpourri, pouncet-box,
   purse atomizer, scent bag, scent ball, scent bottle, scent box,
   scenter, smelling bottle, spray, thurible, vinaigrette