WordNet (r) 3.0 (2006):

prearrangement
    n 1: something arranged in advance

Moby Thesaurus II by Grady Ward, 1.0:

89 Moby Thesaurus words for "prearrangement":
   approach, arrangement, attack, basic training, blueprint,
   blueprinting, briefing, calculation, charting, clearing the decks,
   conception, contrivance, design, device, disposition, enterprise,
   envisagement, equipment, familiarization, figuring, fixing,
   foresight, forethought, foundation, game, graphing, ground plan,
   groundwork, guidelines, idea, intention, layout, lineup,
   long-range plan, makeready, making ready, manufacture, mapping,
   master plan, method, methodology, mobilization,
   operations research, organization, plan, planning,
   planning function, preliminaries, preliminary, preliminary act,
   preliminary step, prep, preparation, preparatory study, preparing,
   prepping, prerequisite, pretreatment, procedure, processing,
   program, program of action, propaedeutic, provision,
   rationalization, readying, schedule, schema, schematism,
   schematization, scheme, scheme of arrangement, setup, spadework,
   strategic plan, strategy, system, systematization, tactical plan,
   tactics, the big picture, the picture, training, treatment, trial,
   tryout, warm-up, way, working plan