The Collaborative International Dictionary of English v.0.48:

Parlor \Par"lor\, n. [OE. parlour, parlur, F. parloir, LL.
   parlatorium. See Parley.] [Written also parlour.]
   1. A room for business or social conversation, for the
      reception of guests, etc. Specifically:
      (a) The apartment in a monastery or nunnery where the
          inmates are permitted to meet and converse with each
          other, or with visitors and friends from without.
          --Piers Plowman.
      (b) In large private houses, a sitting room for the family
          and for familiar guests, -- a room for less formal
          uses than the drawing-room. Esp., in modern times, the
          dining room of a house having few apartments, as a
          London house, where the dining parlor is usually on
          the ground floor.
      (c) Commonly, in the United States, a drawing-room, or the
          room where visitors are received and entertained; a
          room in a private house where people can sit and talk
          and relax, not usually the same as the dining room.
          [1913 Webster +PJC]

   Note: "In England people who have a drawing-room no longer
         call it a parlor, as they called it of old and till
         recently." --Fitzed. Hall.
         [1913 Webster]

   2. A room in an inn or club where visitors can be received.
      [WordNet 1.5]

   Parlor car. See Palace car, under Car.
      [1913 Webster]

WordNet (r) 3.0 (2006):

parlor
    n 1: reception room in an inn or club where visitors can be
         received [syn: parlor, parlour]
    2: a room in a private house or establishment where people can
       sit and talk and relax [syn: living room, living-room,
       sitting room, front room, parlor, parlour]

Moby Thesaurus II by Grady Ward, 1.0:

44 Moby Thesaurus words for "parlor":
   agency, atelier, barbershop, beauty parlor, beauty shop, bench,
   best room, butcher shop, company, concern, corporation, desk,
   drawing room, establishment, facility, firm, foreroom, front room,
   house, installation, institution, living room, loft, lounge,
   organization, reception room, salon, saloon, shop, sitting room,
   solarium, studio, sun parlor, sunroom, sweatshop, work site,
   work space, workbench, workhouse, working space, workplace,
   workroom, workshop, worktable