The Collaborative International Dictionary of English v.0.48:

Treatment \Treat"ment\, n. [Cf. F. traitement. See Treat.]
   1. The act or manner of treating; management; manipulation;
      handling; usage; as, unkind treatment; medical treatment.
      [1913 Webster]

   2. Entertainment; treat. [Obs.]
      [1913 Webster]

            Accept such treatment as a swain affords. --Pope.
      [1913 Webster]

WordNet (r) 3.0 (2006):

treatment
    n 1: care provided to improve a situation (especially medical
         procedures or applications that are intended to relieve
         illness or injury) [syn: treatment, intervention]
    2: the management of someone or something; "the handling of
       prisoners"; "the treatment of water sewage"; "the right to
       equal treatment in the criminal justice system" [syn:
       treatment, handling]
    3: a manner of dealing with something artistically; "his
       treatment of space borrows from Italian architecture"
    4: an extended communication (often interactive) dealing with
       some particular topic; "the book contains an excellent
       discussion of modal logic"; "his treatment of the race
       question is badly biased" [syn: discussion, treatment,
       discourse]

Moby Thesaurus II by Grady Ward, 1.0:

144 Moby Thesaurus words for "treatment":
   airing, analysis, arrangement, article, atmosphere, balance,
   basic training, briefing, brushwork, buzz session, canvassing,
   care, causerie, clearing the decks, colloquium, color, composition,
   conference, consideration, curative measures, cure, curing,
   custodianship, debate, debating, deliberation, descant, design,
   dialectic, dialogue, discourse, discussion, disquisition,
   dissertation, draftsmanship, equipment, essay, etude, examination,
   exchange of views, excursus, exposition, familiarization, feature,
   first aid, first approach, fixing, forum, foundation, groundwork,
   grouping, handling, healing, healing arts, homily, hospitalization,
   introductory study, investigation, joint discussion, line,
   logical analysis, logical discussion, lucubration, makeready,
   making ready, management, manufacture, means of dealing,
   medical care, medical treatment, medicamentation, medication,
   medicines, memoir, mobilization, monograph, morceau, note,
   open discussion, open forum, outline, painterliness, pandect,
   panel discussion, paper, paragraph, perspective, piece, planning,
   prearrangement, preliminaries, preliminary, preliminary act,
   preliminary step, preliminary study, prep, preparation,
   preparatory study, preparing, prepping, prerequisite, pretreatment,
   processing, prolegomenon, propaedeutic, provision, psychotherapy,
   rap, rap session, readying, regime, regimen, research paper,
   review, screed, seminar, shading, shadow, sketch, spadework,
   special article, stewardship, study, survey, symposium, technique,
   term paper, theme, therapeusis, therapeutics, therapy, thesis,
   tone, town meeting, tract, tractate, training, treatise, trial,
   tryout, usage, values, ventilation, warm-up