nonchalant
🇺🇸
/ˌnɑːnʃəˈlɑːnt/
🇬🇧
/ˈnɒnʃələnt/
acting in a relaxed and calm way, showing that you do not care or are not worried about anything
He gave a nonchalant wave and walked away.
他不經意地揮了揮手就走了。