The Collaborative International Dictionary of English v.0.48:

Predisposition \Pre*dis`po*si"tion\, n. [Pref. pre- +
   disposition: cf. F. pr['e]disposition.]
   1. The act of predisposing, or the state of being
      predisposed; previous inclination, tendency, or
      propensity; predilection; -- applied to the mind; as, a
      predisposition to anger.

   Syn: inclination; tendency; predilection; propensity.
        [1913 Webster]

   2. Previous fitness or adaptation to any change, impression,
      or purpose; susceptibility; -- applied to material things;
      as, the predisposition of the body to disease.
      [1913 Webster]

WordNet (r) 3.0 (2006):

predisposition
    n 1: susceptibility to a pathogen [syn: sensitivity,
         predisposition]
    2: an inclination beforehand to interpret statements in a
       particular way
    3: a disposition in advance to react in a particular way

Moby Thesaurus II by Grady Ward, 1.0:

93 Moby Thesaurus words for "predisposition":
   a thing for, affinity, animus, aptitude, aptness, bag, bent, bias,
   cast, character, chosen kind, conatus, conduciveness, constitution,
   cup of tea, delight, diathesis, disposition, druthers, eagerness,
   eccentricity, fancy, favor, feeling for, forejudgment, grain,
   idiosyncrasy, inclination, inclining, individualism, kidney,
   leaning, liability, liking, make, makeup, mental set, mettle, mind,
   mind-set, mold, nature, parti pris, partiality, particular choice,
   penchant, personal choice, preapprehension, preconception,
   preconclusion, preconsideration, predecision, predetermination,
   predilection, preference, prejudgment, prejudication, prejudice,
   premature judgment, prenotion, prepossession, presumption,
   presupposal, presupposition, presurmise, probability, proclivity,
   proneness, propensity, readiness, sensitivity to, set, slant,
   soft spot, stamp, strain, streak, stripe, style, susceptibility,
   taste, temper, temperament, tendency, thing, tropism, turn,
   turn of mind, twist, type, warp, weakness, willingness