The Chinese word **瞳孔** (tóngkǒng), meaning "pupil" (of the eye), is a compound noun formed through semantic combination. The first character, **瞳**, already means "pupil" by itself, composed of the eye radical (**目**) and the phonetic component **童** (tóng). The second character, **孔** (kǒng), means "hole" or "aperture." Therefore, the term **瞳孔** literally and descriptively combines the concepts of "pupil" and "hole" to specify the anatomical opening in the iris, creating a precise and visually logical term for the black circular aperture through which light enters the eye.