The Collaborative International Dictionary of English v.0.48:

Fixture \Fix"ture\ (f[i^]ks"t[-u]r; 135), n. [Cf. Fixure.]
   1. That which is fixed or attached to something as a
      permanent appendage; as, the fixtures of a pump; the
      fixtures of a farm or of a dwelling, that is, the articles
      which a tenant may not take away.
      [1913 Webster]

   2. State of being fixed; fixedness.
      [1913 Webster]

            The firm fixture of thy foot.         --Shak.
      [1913 Webster]

   3. (Law) Anything of an accessory character annexed to houses
      and lands, so as to constitute a part of them. This term
      is, however, quite frequently used in the peculiar sense
      of personal chattels annexed to lands and tenements, but
      removable by the person annexing them, or his personal
      representatives. In this latter sense, the same things may
      be fixtures under some circumstances, and not fixtures
      under others. --Wharton (Law Dict.). --Bouvier.
      [1913 Webster]

   Note: This word is frequently substituted for fixure
         (formerly the word in common use) in new editions of
         old works.
         [1913 Webster]

WordNet (r) 3.0 (2006):

fixture
    n 1: an object firmly fixed in place (especially in a household)
    2: a regular patron; "an habitue of the racetrack"; "a bum who
       is a Central Park fixture" [syn: regular, habitue,
       fixture]
    3: the quality of being fixed in place as by some firm
       attachment [syn: fastness, fixedness, fixity,
       fixture, secureness] [ant: looseness]
    4: the act of putting something in working order again [syn:
       repair, fix, fixing, fixture, mend, mending,
       reparation]

Moby Thesaurus II by Grady Ward, 1.0:

143 Moby Thesaurus words for "fixture":
   accession, accessory, accompaniment, accouterments, addenda,
   addendum, additament, addition, additive, additory, additum,
   adjunct, adjuvant, annex, annexation, appanage, apparatus,
   appendage, appendant, appliance, appliances, appointments,
   appurtenance, appurtenances, appurtenant, armament, attachment,
   augment, augmentation, brassware, chinaware, clayware, coda,
   complement, concomitant, confirmation, continuation, contrivance,
   convenience, conveniences, copperware, corollary, deep-rootedness,
   deep-seatedness, device, dinnerware, drive, duffel, durable goods,
   durables, earthenware, embedment, enamelware, engine, enginery,
   entrenchment, equipage, equipment, establishment, event, extension,
   extrapolation, facilities, facility, fitting, fittings, fixation,
   fixedness, fixity, fixtures, flatware, furnishings, furniture,
   gadget, gear, glassware, graniteware, hard goods, hardware,
   hollow ware, housefurnishings, housewares, impedimenta,
   implantation, increase, increment, infixion, installations,
   institution, instrument, inveteracy, ironmongery, ironware, kit,
   kitchenware, machine, machinery, match, materiel, mechanical aid,
   mechanical device, mechanism, meet, meeting, metalware,
   motive power, motor, munition, munitions, occasion, occurrence,
   offshoot, outfit, ovenware, paraphernalia, pendant, plant,
   plumbing, power plant, power source, reinforcement, rig, rigging,
   side effect, side issue, silverware, sporting goods, stabilization,
   stock-in-trade, stoneware, supplement, tableware, tackle,
   tailpiece, things, tinware, tool, tools and machinery,
   undergirding, utensils, utility, white goods, woodenware