To enhance the mass of hair, which term would be most appropriate to use?

The term "volume" is the most appropriate choice when discussing enhancing the mass of hair. In hairstyling, volume refers specifically to the amount of space that hair occupies, which is often associated with fullness and body. When stylists aim to enhance volume, they typically use techniques such as layering, curling, or using specific products that create lift at the roots. This leads to the perception of thicker, fuller hair, which contributes to an overall increase in the appearance of mass.

While "weight" can refer to the heaviness of hair, it does not directly relate to the fullness or body that volume achieves. "Size" is a less specific term that does not encapsulate the particular qualities of hair fullness. "Density" refers to the number of individual hair strands per unit area on the scalp and, although it can influence how thick hair appears, it does not directly apply to the styling techniques used to create visual volume in the hair. Therefore, "volume" is the most relevant term when seeking to enhance the appearance of mass in hair styling.