spandex

The generic name of man-made fibers derived from a chemical substance called segmented polyurethane (resin). This man-made elastic fiber has a good deal of stretch and recovery for its weight. Spandex is used extensively in foundation garments and is much more comfortable than rubber because it is lighter in weight. Spandex is also found in some fabrics where stretch is considered desirable, such as in ski clothes. See polyurethane.