Insouciance (noun)

1. A feeling of not being worried or concerned about something.
2. An attitude or manner that suggests a lack of concern or care.

Origin:

French, from insouciant, present participle of s'insoucier to be unconcerned, from old french en- + soucier to worry.

Examples:

1. His insouciance in the face of danger was admirable.
2. Her insouciance towards the money made her seem like a wealthy person.
3. The young man's insouciance about his future was a cause of concern for his parents.
4. Despite the urgency of the situation, he maintained an air of insouciance.
5. The players displayed insouciance throughout the game, never seeming to take it seriously.