The Collaborative International Dictionary of English v.0.48:

Workshop \Work"shop`\, n.
   A shop where any manufacture or handiwork is carried on.
   [1913 Webster]

WordNet (r) 3.0 (2006):

workshop
    n 1: small workplace where handcrafts or manufacturing are done
         [syn: workshop, shop]
    2: a brief intensive course for a small group; emphasizes
       problem solving

Moby Thesaurus II by Grady Ward, 1.0:

31 Moby Thesaurus words for "workshop":
   agency, atelier, barbershop, beauty parlor, beauty shop, bench,
   butcher shop, company, concern, corporation, desk, establishment,
   facility, firm, house, installation, institution, loft,
   organization, parlor, shop, studio, sweatshop, work site,
   work space, workbench, workhouse, working space, workplace,
   workroom, worktable