See unconcern in Webster's New World Roget's A-Z Thesaurus II
noun
Lack of emotion or interest:
apathy, disinterest, impassivity, incuriosity, incuriousness, indifference, insensibility, insensibleness, lassitude, lethargy, listlessness, phlegm, stolidity, stolidness, uninterest, unresponsiveness. See feelings
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