“惘然”是一个比较书面的词，意思是心里很失落、不知道该怎么办，好像丢了什么东西一样。

"惘然" is a somewhat literary word meaning feeling lost and unsure what to do, as if something is missing.

我们常常说“惘然若失”，用来形容一个人发呆、心里空空的样子。

We often say "惘然若失" to describe someone who is dazed and feeling empty inside.