n.[U]

1. 明亮；光亮度
   The lightness of the sky showed that the rain was really over.

   天空明亮表示雨确已停了。

2. （颜色的）浅淡

n.[U]

1. 轻，轻微
2. 轻快，敏捷
3. 愉快；轻松
   That gave one sense of lightness.

   它给人一种轻松感。

4. 轻率；轻浮
   Such lightness of conduct is not to be permitted in church.

   做礼拜时，不允许这种轻浮行为。