1. 漠不关心的;漫不经心的
An insouciant action or quality shows someone's lack of concern about something which they might be expected to take more seriously.

1. marked by blithe unconcern

e.g. an ability to interest casual students
showed a casual disregard for cold weather
an utterly insouciant financial policy
an elegantly insouciant manner
drove his car with nonchalant abandon
was polite in a teasing nonchalant manner

Synonym: casualnonchalant