lightheartedness

1. It is peace and gentleness and lightheartedness.
   幸福是一种平和，柔顺和无忧无虑的状态。
2. This apparent lightheartedness does not conceal the real contempt that many men feel for women.
   可这表面现象却无法掩饰许多男人对女性所抱的鄙视态度。
3. But research shows that bursts of lightheartedness, whether from a smile shared with a colleague or a funny clip on YouTube, actually cause people to think more clearly and creatively.
   但是研究发现，无论是和同事说笑，还是在YouTube上看到一个搞笑视频，不时的轻松情绪都会让人更加清醒和有创造力。

noun

1. the cheerful feeling you have when nothing is troubling you

   Synonym:    carefreenessinsouciancelightsomeness