The Collaborative International Dictionary of English v.0.48:

Factory \Fac"to*ry\, n.; pl. Factories (-r[i^]z). [Cf. F.
   factorerie.]
   1. A house or place where factors, or commercial agents,
      reside, to transact business for their employers. "The
      Company's factory at Madras." --Burke.
      [1913 Webster]

   2. The body of factors in any place; as, a chaplain to a
      British factory. --W. Guthrie.
      [1913 Webster]

   3. A building, or collection of buildings, appropriated to
      the manufacture of goods; the place where workmen are
      employed in fabricating goods, wares, or utensils; a
      manufactory; as, a cotton factory.
      [1913 Webster]

   Factory leg (Med.), a variety of bandy leg, associated with
      partial dislocation of the tibia, produced in young
      children by working in factories.
      [1913 Webster]

WordNet (r) 3.0 (2006):

factory
    n 1: a plant consisting of one or more buildings with facilities
         for manufacturing [syn: factory, mill, manufacturing
         plant, manufactory]

Moby Thesaurus II by Grady Ward, 1.0:

47 Moby Thesaurus words for "factory":
   armory, arsenal, assembly line, assembly plant,
   atomic energy plant, bindery, boatyard, boilery, bookbindery,
   brewery, brickyard, cannery, creamery, dairy, defense plant,
   distillery, dockyard, factory belt, factory district, feeder plant,
   flour mill, industrial park, industrial zone, main plant,
   manufactory, manufacturing plant, manufacturing quarter, mill,
   mint, munitions plant, oil refinery, packing house, plant, pottery,
   power plant, production line, push-button plant, refinery, sawmill,
   shipyard, subassembly plant, sugar refinery, tannery, winery,
   works, yard, yards



Bouvier's Law Dictionary, Revised 6th Ed (1856):

FACTORY, Scotch law. A contract which partakes of a mandate and locatio ad
operandum, and which is in the English and American law books discussed
under the title of Principal and Agent. 1 Bell's Com. 259.