‘脸’ (liǎn) means 'face', and ‘色’ (sè) means 'color' or 'complexion'. Together, 脸色 literally means 'face color', but it refers to the visible appearance of a person’s face — especially changes that reflect physical condition or emotional state. Unlike English 'facial expression', which emphasizes intentional gestures (e.g., smiling or frowning), 脸色 focuses on involuntary, often subtle cues: paleness from illness, redness from embarrassment or fever, or sallowness from fatigue.

This term is commonly used in health-related contexts ('His 脸色 looks pale — maybe he has low blood pressure') and interpersonal observations ('Her 脸色 darkened when she heard the news'). It carries connotations of authenticity — people may try to hide their emotions, but 脸色 often betrays them. It's neutral in register, appearing in both spoken and written Chinese, though slightly more formal than colloquial alternatives like 表情 (biǎoqíng).