Final answer:
The element of hair design that relates to the mass or general outline of a hairstyle is the mass, which is the hairstyle's three-dimensional volume and shape.
Step-by-step explanation:
The element of hair design that relates to the mass or general outline of a hairstyle is known as the mass of the hairstyle. The mass constitutes the three-dimensional volume and the overall shape of the hairstyle. This is similar to how mass in art and architecture is defined, relating to weight, density, and bulk that contribute to the object's presence in space. For instance, a compact and intricate bun has less mass than a voluminous and fluffy african hairstyle. Similarly, in ancient civilizations, hairstyles were significant in conveying several sociocultural messages, and their mass would often contribute to that communication. Hair's significance in cultures worldwide, its status as an artistic representation, and sciences such as evolutionary biology further emphasize the importance of understanding the concept of mass in hair design.