The state of being light-hearted or free from care or grief; cheerfulness; playfulness.(noun)
The Century Dictionary (Public Domain)
Use "light-heartedness" in a sentence
"If flippancy and light-heartedness characterize much of Oscar Wilde's writing, a more sober, even somber, outlook shadows his prison writings."
"We'll see whether that light-heartedness extends to how this grown-up Dick Grayson feels about working with Bruce Wayne again."
"I was the only one present that could observe the subtle dance with even a tinge of humor, of light-heartedness, and still I could begin to somewhat understand Brandon's long-time obsession with not standing in line."