Synonyms for Unconcerned (same or very similar meaning)
WordNet sense 1 (showing no care or concern in attitude or action):
indifferent
WordNet sense 2 (showing lack of emotional involvement):
detached
WordNet sense 3 (marked by blithe unconcern):
insouciant, nonchalant
WordNet sense 4 (lacking or showing a lack of due concern):
blithe
From the ODE community, based on WordNet
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