The crossword solution for the term 'A LONG, NARROW MARK' is LINE. A LINE is a basic element of art and design, consisting of a point moving in space. Lines can be used to create shapes, patterns, and textures, as well as to divide and organize space. Lines can be straight, curved, or jagged, and can be used to create a variety of effects. Lines are often used to create a sense of movement, depth, and texture in artwork.