too serious and disapproving

Two po-faced men came to inspect the house. 两个面容严肃的男子来检查这间房子。

The film is serious but not po-faced. 这部电影很严肃但并不呆板乏味。

A po-faced person has a face with a serious, disapproving, or empty expression.

She remained po-faced all evening, even when the rest of us were in stitches at Bob's jokes. 她整个晚上都不苟言笑，即使在其他人因为鲍勃的笑话笑破了肚皮时也是如此。