Which word refers to the facial appearance or expression of a person?

The term that refers specifically to the facial appearance or expression of a person is "countenance." This word derives from the Latin "componere," which means "to put together," and it captures the idea of the face as a whole, often reflecting emotions or personality traits. Countenance can indicate a variety of states such as happiness, sadness, anger, or calmness.

While "visage" also pertains to a person's face, it is more general and can refer to the shape or features rather than the expression itself. "Facade" typically describes the front exterior of a building or a deceptive outward appearance, lacking the personal and emotional connotation of facial expression. "Aspect," on the other hand, refers to a particular part or feature of something and does not specifically focus on facial appearance.

In summary, "countenance" precisely encapsulates the idea of expressing emotions through facial features, making it the most appropriate choice for this context.