The Collaborative International Dictionary of English v.0.48:

Supplier \Sup*pli"er\, n.
   One who supplies.
   [1913 Webster]

WordNet (r) 3.0 (2006):

supplier
    n 1: someone whose business is to supply a particular service or
         commodity [syn: supplier, provider]

Moby Thesaurus II by Grady Ward, 1.0:

20 Moby Thesaurus words for "supplier":
   caterer, chandler, commissariat, commissary, donor, furnisher,
   manciple, merchant, patron, provider, provisioner, purveyor,
   quartermaster, retailer, steward, stock clerk, storekeeper, sutler,
   victualer, vivandier