lightsomeness

(noun) the cheerful feeling you have when nothing is troubling you. Synonyms: carefreeness, insouciance, lightheartedness.

(noun) the gracefulness of a person or animal that is quick and nimble. Synonyms: agility, legerity, lightness, nimbleness.

(noun) the trait of being lighthearted and frivolous. Synonyms: lightness.