nonchalant
adjective uk/ˈnɒn.ʃəl.ənt/ us/ˌnɑːn.ʃəˈlɑːnt/
若无其事的;漠不关心的;毫不在乎的
behaving in a calm manner, often in a way that suggests you are not interested or do not care
a nonchalant manner/shrug 冷淡的态度／不屑的耸肩
Synonyms: carefreecareless (NO WORRY) casualhappy-go-lucky