Denier

A weight-per-unit-length measure of filament fibers or yarns. Denier is numerically equal to the weight in grams of 9,000 meters of fiber. Denier is a direct numbering system in which the lower numbers represent the finer sizes and the higher numbers the coarser sizes. In the U.S., the denier system is used for numbering filament yarns and man-made fiber staple (but not spun yarns).