プログレッシブ和英中辞典(第4版)の解説
むとんじゃく【無頓着】
無頓着な 〔無関心な〕indifferent ((to))；〔気にしない〕unconcerned ((about))，careless ((about)) ⇒むかんしん（無関心）
服装に無頓着だ
He is careless about his clothes.
人の感情に無頓着だ
He is unmindful of other people's feelings.
彼は自分の評判には無頓着だ
He is totally 「indifferent to [unconcerned about] his own reputation.
細かい点に無頓着だ
He 「does not care about [pays no attention to/is inattentive to] detail.