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indifferent; unconcerned; nonchalant; unmindful; inattentive; careless
彼は服装に無頓着で同じ服ばかり着ている。
He is indifferent to clothing and always wears the same outfit.
健康に無頓着な生活を改めるべきだ。
You should change your lifestyle of being unconcerned about health.
周囲の評判に無頓着な態度が批判を招いた。
Their nonchalant attitude toward public reputation invited criticism.