levity
/ˈlevətɪ/noun
mass noun
- the treatment of a serious matter with humour or in a manner lacking due respect（指对待严肃事情时表现出来的）轻松逗趣的态度; 不敬; 轻浮; 不庄重：
as an attempt to introduce a note of levity, the words were a disastrous flop.
本想把话说得轻松诙谐点儿, 没想到结果会这么糟。
词源
mid 16th cent.: from Latin levitas, from levis 'light'.