昏 (hūn): Mùi-đầu

He pulled two all-nighters in a row; in class today his head was so muddled that he couldn't take in anything the teacher said.

That muddle-headed ruler spent all day drinking and making merry, ignored state affairs, and ultimately caused the nation's downfall.

The room was too dim; after reading for a long time my eyes became blurry, so I had to turn on the desk lamp to continue studying.