Insouciant

She gave an insouciant look.

an insouciant gesture

"I am quite serious in saying that your loss must and would be felt; but I verily believe," added she, after a moment's hesitation, "that you are so insouciant yourself, that you cannot believe that every body else is not equally indifferent."

It was there [Cadiz, Spain] that on Sunday I had seen the populace disport itself, and it was full of life then, gay and insouciant.

When we left the Marr house, he [Peter] had boldly said to Felicity, "May I see you home?" And Felicity, much to our amazement, had taken his arm and marched off with him. […] As for me, I was consumed by a secret and burning desire to ask the Story Girl if I might see her home; but I could not screw my courage to the sticking point. How I envied Peter his easy, insouciant manner!

[…] [Jack] Nicholson turned to an assistant, bummed a cigarette, flashed one of his wolfish, insouciant grins and said, "We all have our little secrets, Seany."

As a fashion editor, I pay obsessive attention to my appearance. Even when I pretend to look insouciant, each look has been painfully considered. The right earrings, coordinating shoes, the careful symmetry of a well-balanced look — these are things that please me. The gym has crushed my sartorial ambitions.