Lycra is a brand name for elastane, which is a synthetic fiber known for exceptional elasticity. It's a segmented polyurethane copolymer that can stretch 500% without breaking and return to its original shape. Macroglycol and diisocyanate are chemical precursors used to make elastane, not the finished product name. Swimsuits are a common application of Lycra fabric but not the material itself. The term 'elastane' is the generic fiber name used worldwide, while 'spandex' is used primarily in North America.