What is the term for a thin, continuous mark used as a guide in hairstyling?

The term for a thin, continuous mark used as a guide in hairstyling is referred to as a line. In hairstyling, lines serve as fundamental elements in creating various styles and shapes. They provide structure and direction, helping stylists to define the cut, outline the shape of a hairstyle, and create visual flow within a haircut. Lines can be straight or curved, and they are essential in establishing the contours and overall design of a hairstyle.

While curves and shapes are important aspects of hairstyling, they are more about the overall style and design rather than serving as a guiding mark. An outline generally refers to a broader definition that may cover multiple aspects, but it lacks the specificity and precision of the term 'line.' Therefore, in the context of hairstyling, 'line' is the term that most accurately describes the thin, continuous mark that serves as a guide.