The Collaborative International Dictionary of English v.0.48:

Indisposition \In*dis`po*si"tion\, n. [Cf. F. indisposition.]
   [1913 Webster]
   1. The state of being indisposed; disinclination; as, the
      indisposition of two substances to combine.
      [1913 Webster]

            A general indisposition towards believing.
                                                  --Atterbury.
      [1913 Webster]

   2. A slight disorder or illness.
      [1913 Webster]

            Rather as an indisposition in health than as any set
            sickness.                             --Hayward.
      [1913 Webster]

WordNet (r) 3.0 (2006):

indisposition
    n 1: a slight illness
    2: a certain degree of unwillingness; "a reluctance to commit
       himself"; "his hesitancy revealed his basic indisposition";
       "after some hesitation he agreed" [syn: reluctance,
       hesitancy, hesitation, disinclination, indisposition]

Moby Thesaurus II by Grady Ward, 1.0:

118 Moby Thesaurus words for "indisposition":
   abnormality, acute disease, affection, affliction, ailment,
   allergic disease, allergy, antipathy, atrophy, averseness,
   aversion, backwardness, bacterial disease, bad books, birth defect,
   blight, cardiovascular disease, chronic disease,
   circulatory disease, complaint, complication, condition,
   congenital defect, cursoriness, defect, deficiency disease,
   deformity, degenerative disease, disability, disagreement, disease,
   disfavor, disinclination, disliking, disobedience, disorder,
   displeasure, disrelish, dissatisfaction, dissent, distaste,
   distemper, endemic, endemic disease, endocrine disease,
   epidemic disease, foot-dragging, fractiousness, functional disease,
   fungus disease, gastrointestinal disease, genetic disease,
   grudging consent, grudgingness, handicap, hereditary disease,
   iatrogenic disease, illness, indisposedness, indocility,
   infectious disease, infirmity, intractableness, lack of enthusiasm,
   lack of zeal, malady, malaise, morbidity, morbus, muscular disease,
   mutinousness, neurological disease, nolition, nutritional disease,
   obstinacy, occupational disease, opposition, organic disease,
   pandemic disease, pathological condition, pathology,
   perfunctoriness, plant disease, protozoan disease,
   psychosomatic disease, recalcitrance, recalcitrancy,
   refractoriness, refusal, reluctance, renitence, renitency,
   repugnance, resistance, respiratory disease, rockiness,
   secondary disease, seediness, sickishness, sickness, signs,
   slowness, stubbornness, sulk, sulkiness, sulks, sullenness,
   symptomatology, symptomology, symptoms, syndrome, the pip,
   unenthusiasm, unwillingness, urogenital disease, virus disease,
   wasting disease, worm disease