Pile is the raised surface or nap of a fabric, consisting of upright loops or strands of yarn.[1] Examples of pile textiles are carpets, corduroy, velvet, plush, and Turkish towels.[2] The word is derived from Latin pilus for "hair".[3]
The surface and the yarn in these fabrics are also called "pile". In particular "pile length" or "pile depth" refer to the length of the yarn strands (half-length of the loops). Pile length affects and is affected by knot density: "The greater the knot density, the thinner the weft and warp yarns and the more weakly are they twisted; the smaller the density, the coarser are the foundation yarns."[4] Designs and motifs are also affected by and affect pile depth: "A carpet design with a high knot density is better adapted to intricate and curvilinear designs, which of necessity must have a shorter pile length to avoid looking blurry. A carpet with a lesser knot density is better adapted to bold, geometric designs and can utilize a long pile for softer, more reflective surface that appeals to the sense of touch."[5]
