The Collaborative International Dictionary of English v.0.48:

Disinterest \Dis*in"ter*est\, p. a.
   Disinterested. [Obs.]
   [1913 Webster]

         The measures they shall walk by shall be disinterest
         and even.                                --Jer. Taylor.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Disinterest \Dis*in"ter*est\, n.
   1. What is contrary to interest or advantage; disadvantage.
      [Obs.] --Glanvill.
      [1913 Webster]

   2. Indifference to profit; want of regard to private
      advantage; disinterestedness. [Obs.] --Johnson.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Disinterest \Dis*in"ter*est\, v. t.
   To divest of interest or interested motives. [Obs.]
   --Feltham.
   [1913 Webster]

WordNet (r) 3.0 (2006):

disinterest
    n 1: tolerance attributable to a lack of involvement [syn:
         disinterest, neutrality]

Moby Thesaurus II by Grady Ward, 1.0:

134 Moby Thesaurus words for "disinterest":
   Olympian detachment, accidia, acedia, aloofness, altruism, apathy,
   ataraxia, ataraxy, benumbedness, blah, blahs, blunt, boredom,
   carelessness, casualness, chill, comatoseness, commitment,
   consecration, cool, damp, dampen, dedication, deflect, detachment,
   deter, devotion, disaffect, discourage, disincline,
   disinterestedness, dispassion, dispassionateness, disregard,
   disregardfulness, distract, divert, dullness, easygoingness,
   heartlessness, hebetude, heedlessness, hopelessness, humility,
   impartiality, impassiveness, impassivity, inappetence, inattention,
   incuriosity, incuriousness, indifference, indifferentism,
   indifferentness, indiscrimination, indispose, inexcitability,
   insouciance, intellectual inertia, lack of affect,
   lack of appetite, lack of interest, lackadaisicalness, languidness,
   lassitude, lethargicalness, lethargy, listlessness, loftiness,
   mindlessness, modesty, negligence, neutrality, nonchalance,
   numbness, passiveness, passivity, phlegm, phlegmaticalness,
   phlegmaticness, plucklessness, pococurantism, put off, quench,
   recklessness, regardlessness, repel, resignation, resignedness,
   sacrifice, self-abasement, self-abnegation, self-denial,
   self-devotion, self-effacement, self-forgetfulness,
   self-immolation, self-neglect, self-neglectfulness,
   self-renouncement, self-sacrifice, self-subjection, selflessness,
   sloth, sluggishness, sopor, soporifousness, spiritlessness,
   spunklessness, stolidity, stupefaction, stupor, supineness,
   torpidity, torpidness, torpor, turn aside, turn away, turn from,
   turn off, unacquisitiveness, unanxiousness, unbias, unbiasedness,
   unconcern, uninquisitiveness, uninterestedness, unmindfulness,
   unpossessiveness, unselfishness, unsolicitousness, wean from,
   withdrawal, withdrawnness