disappointed or unhappy, and quiet

You look glum. What's up? 你看上去闷闷不乐的，怎么了？

He's very glum about the company's prospects. 他对公司的前景感到很不乐观。

If a place is glum, it is not attractive and has nothing that causes pleasure.

They live in one glum little room. 他们住在一间死气沉沉的小房间里。