The Chinese word **垂直** (chuízhí), meaning "vertical" or "perpendicular," is a logical compound formed by combining two characters: **垂** (chuí), which carries the core meaning of "to hang down" or "dangle," and **直** (zhí), which means "straight." Their semantic union creates the vivid image of something hanging in a perfectly straight line downward, which directly corresponds to the geometric concept of being at a right angle to a horizontal base. Thus, the term is a descriptive, ideographic construction where the combined meanings of its components perfectly capture the essence of the abstract spatial relationship it denotes.