lightness of mind, character, or behavior; lack of appropriate seriousness or earnestness.

an instance or exhibition of this.

fickleness.

lightness in weight.

noun

gravity , seriousness

noun

absurdity , amusement , buoyancy , facetiousness , festivity , fickleness , flightiness , flippancy , folly , foolishness , frivolity , giddiness , happiness , high spirits , hilarity , jocularity , laughs , lightheartedness , mirth , picnic * , pleasantry , repartee , trifling , triviality , volatility , wit , fun , gayety , humor , humour , inconstancy , lightness , silliness