“It was just better for the story arc,” David insouciantly observed.
"Not to-day, thanks," retorted Tess insouciantly—that was another quality Missy envied in her friend, her unfailing insouciance.
The blood of his actress mother carried him insouciantly over the pregnant silence that received him.
And then he took the high note—took it easily, insouciantly—held it, trilled it, tossed it.
He who had insouciantly reassured Mother had himself to choke down the timorous speculations of a shop-bound clerk.
unconcerned, undisturbed; carefree and nonchalant
Latin in- + soucier 'to disturb'