levity

levity is a Noun

Definition:

[1] The quality of weighing less than something else of equal bulk; relative lightness, especially as shown by rising through, or floating upon, a contiguous substance; buoyancy; -- opposed to gravity. He gave the form of levity to that which ascended; to that which descended, the form of gravity. Sir. W. Raleigh. This bubble by reason of its comparative levity to the fluidity that incloses it, would ascend to the top. Bentley.

[2] Lack of gravity and earnestness in deportment or character; trifling gayety; frivolity; sportiveness; vanity. " A spirit of levity and libertinism." Atterbury. He never employed his omnipotence out of levity. Calamy.

[3] Lack of steadiness or constancy; disposition to change; fickleness; volatility. The levity that is fatigued and disgusted with everything of which it is in possession. Burke.