The term 'FINE LINE' can be broken down into two crossword solutions: 'THREAD' (6 letters) and 'STRIA' (5 letters). 'THREAD' is a thin strand of material, usually made of cotton, linen, wool, or synthetic fiber, used in sewing and weaving. 'Stria' is a thin line or stripe, often found in nature, such as the striations on a rock or the stripes on a zebra. Together, these two words form the phrase 'fine line, ' which is used to describe a subtle distinction between two things, or a delicate balance between two opposing forces.