insouciant
[ɪnˈsuːʃɑnt]
Definitions
1. adjective
lacking or showing a carefree and nonchalant attitude
“She walked into the party with an insouciant smile, as if nothing could bother her.”
2. noun
a person who is carefree and nonchalant
“The insouciant young artist was known for his carefree attitude towards his art.”