The Collaborative International Dictionary of English v.0.48:

Organize \Or"gan*ize\ ([^o]r"gan*[imac]z), v. t. [imp. & p. p.
   Organized ([^o]r"gan*[imac]zd); p. pr. & vb. n.
   Organizing ([^o]r"gan*[imac]*z[i^]ng).] [Cf. F. organiser,
   Gr. 'organi`zein. See Organ.]
   1. (Biol.) To furnish with organs; to give an organic
      structure to; to endow with capacity for the functions of
      life; as, an organized being; organized matter; -- in this
      sense used chiefly in the past participle.
      [1913 Webster]

            These nobler faculties of the mind, matter organized
            could never produce.                  --Ray.
      [1913 Webster]

   2. To arrange or constitute in parts, each having a special
      function, act, office, or relation; to systematize; to get
      into working order; -- applied to products of the human
      intellect, or to human institutions and undertakings, as a
      science, a government, an army, a war, etc.
      [1913 Webster]

            This original and supreme will organizes the
            government.                           --Cranch.
      [1913 Webster]

   3. (Mus.) To sing in parts; as, to organize an anthem. [R.]
      --Busby.
      [1913 Webster]

WordNet (r) 3.0 (2006):

organize
    v 1: create (as an entity); "social groups form everywhere";
         "They formed a company" [syn: form, organize,
         organise]
    2: cause to be structured or ordered or operating according to
       some principle or idea [syn: organize, organise] [ant:
       disorganise, disorganize]
    3: plan and direct (a complex undertaking); "he masterminded the
       robbery" [syn: mastermind, engineer, direct,
       organize, organise, orchestrate]
    4: bring order and organization to; "Can you help me organize my
       files?" [syn: organize, organise, coordinate]
    5: arrange by systematic planning and united effort; "machinate
       a plot"; "organize a strike"; "devise a plan to take over the
       director's office" [syn: organize, organise, prepare,
       devise, get up, machinate]
    6: form or join a union; "The auto workers decided to unionize"
       [syn: unionize, unionise, organize, organise]

Moby Thesaurus II by Grady Ward, 1.0:

152 Moby Thesaurus words for "organize":
   adjust, affiliate, ally, arrange, array, assemble, associate,
   band together, be in cahoots, begin, build, build up, bunch,
   bunch up, cabal, calculate, cast, catalogue, categorize,
   cement a union, centralize, chart, classify, club, club together,
   codify, combine, come together, compose, concert, confederate,
   consist of, consociate, conspire, constitute, construct, contrive,
   cool off, coordinate, couple, create, cut out, deploy, design,
   develop, devise, dispose, effect, effectuate, embody, enter into,
   establish, fabricate, federalize, federate, figure, fix, forecast,
   form, found, frame, gang, gang up, go in partners,
   go in partnership, go into, grade, group, harmonize, hierarchize,
   hook up with, inaugurate, incept, incorporate, initiate, install,
   institute, integrate, intend, join, join forces,
   join fortunes with, join together, join up with, join with,
   lay out, lay plans, league, line up, make, make a projection,
   make arrangements, make up, marry, marshal, materialize, merge in,
   methodize, mix, muster, normalize, order, originate, pacify, pair,
   pair off, partner, piece together, plan, plan ahead, prearrange,
   program, project, put together, quiet, rally, rank, rationalize,
   realize, regularize, regulate, routinize, schedule, schematize,
   set up, settle, shape, sort out, stand together, stand up with,
   standardize, start, structure, synchronize, synthesize,
   systematize, systemize, tabulate, team up with, team with,
   throw in with, tie in with, tie up with, tranquilize, tune,
   tune up, unionize, unite in, unite with, wed, work out, work up