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easy; easygoing; carefree; happy-go-lucky; optimistic; leisurely; careless; thoughtless
締め切り前なのに暢気に昼寝をしている。
He's napping leisurely even though the deadline is approaching.
彼女は暢気な性格で何事も気にしない。
She has an easygoing personality and doesn't worry about anything.
暢気に構えていたら電車に乗り遅れた。
I took things too easy and missed the train.