levity

A lightness of manner or speech, frivolity; flippancy; a lack of appropriate seriousness; an inclination to make a joke of serious matters.

A lack of steadiness.

The state or quality of being light, buoyancy.

Most of the confidences were unsought - frequently I have feigned sleep, preoccupation or a hostile levity […]

[…]it would really seem as if there was something nomadic in our natures, a principle of levity and restlessness […]

A lighthearted or frivolous act.

For though it be something wonderful to tell that any should have hearts so hardened, in the midst of such a calamity, as to rob and steal, yet certain it is that all sorts of villainies, and even levities and debaucheries, were then practiced in the town as openly as ever: I will not say quite as frequently, because the number of people were many ways lessened.

[…] or do the people joy less than common in their levities?"