(1):
(n.) 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.
(2):
(n.) Lack of gravity and earnestness in deportment or character; trifling gayety; frivolity; sportiveness; vanity.
(3):
(n.) Lack of steadiness or constancy; disposition to change; fickleness; volatility.