frivolousness

a lack of seriousness often at an improper time his childish frivolousness at the awards ceremony wasn't appreciated by anyone Synonyms facetiousness, flightiness, flippancy, frivolity, frothiness, levity, light-headedness, light-mindedness, lightness, sillinessRelated Words cheer, cheerfulness, festivity, gaiety (also gayety), glee, gleefulness, high-spiritedness, hilarity, joviality, lightheartedness, merriment, mirth, mirthfulness; childishness, goofiness, puerilityNear Antonyms dejection, depression, despondency, dispiritedness, downheartedness, gloom, gloominess, heartsickness, joylessness, melancholy, mopes, moroseness, sadness, sullenness, unhappinessAntonyms earnestness, gravity, seriousness, soberness, solemnity, solemnness