What term refers to the thickness or diameter of an individual hair strand?

The term that refers to the thickness or diameter of an individual hair strand is known as texture. In the context of hair, 'texture' encompasses both the thickness of individual strands and the overall feel of the hair, such as whether it is coarse, fine, or somewhere in between. Understanding hair texture is crucial in the field of waxing and other hair removal services, as it influences how hair responds to waxing techniques and products.

Density, while it pertains to the number of hair strands in a given area, does not specifically refer to the thickness of each strand. Length refers solely to how long the hair strands are but does not provide any information about their thickness. Color describes the pigment of the hair and does not relate to its structural characteristics. Thus, texture accurately captures the concept of strand thickness, making it the correct answer in this context.