The Collaborative International Dictionary of English v.0.48:

Incuriosity \In*cu`ri*os"i*ty\, n. [L. incuriositas: cf. F.
   incurosit['e].]
   Lack of curiosity or interest; inattentiveness; indifference.
   --Sir H. Wotton.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

59 Moby Thesaurus words for "incuriosity":
   absentmindedness, accidia, acedia, apathy, ataraxia, ataraxy,
   carelessness, casualness, detachment, disinterest, dispassion,
   disregard, disregardfulness, distraction, easygoingness,
   flightiness, flippancy, frivolousness, giddiness, heedlessness,
   inadvertence, inadvertency, inattention, inattentiveness,
   inconsideration, indifference, indiscrimination, inexcitability,
   inobservance, insouciance, lack of affect, lackadaisicalness,
   levity, lightmindedness, listlessness, mindlessness, negligence,
   nonchalance, nonobservance, obliviousness, pococurantism,
   recklessness, regardlessness, shallowness, sloth, superficiality,
   thoughtlessness, unalertness, unanxiousness, unawareness,
   unconcern, unconsciousness, unheedfulness, unintentiveness,
   unmindfulness, unobservance, unsolicitousness, unwariness,
   unwatchfulness