Unconcern(n.) Want of concern; absence of anxiety; freedom from solicitude; indifference.
Thesaurus Entries
accidia, acedia, aloofness, apathy, ataraxia, ataraxy, benumbedness, blah, blahs, boredom, carelessness, casualness, comatoseness, detachment, disinterest, disinterestedness, dispassion, disregard, disregardfulness, dullness, easygoingness, heartlessness, hebetude, heedlessness, hopelessness, impassiveness, impassivity, inappetence, inattention, incuriosity, incuriousness, indifference, indifferentism, indifferentness, indiscrimination, inexcitability, insouciance, intellectual inertia, lack of affect, lack of appetite, lack of interest, lackadaisicalness, languidness, lassitude, lethargicalness, lethargy, listlessness, mindlessness, negligence, nonchalance, numbness, offhandedness, passiveness, passivity, phlegm, phlegmaticalness, phlegmaticness, plucklessness, pococurantism, recklessness, regardlessness, resignation, resignedness, sloth, sluggishness, sopor, soporifousness, spiritlessness, spunklessness, stolidity, stupefaction, stupor, supineness, torpidity, torpidness, torpor, unanxiousness, uninquisitiveness, uninterestedness, unmindfulness, unsolicitousness, withdrawal, withdrawnness