Elastic fiber, also known as Lycra (5 letters), is a synthetic fiber that is used in a variety of clothing and other products. It is known for its elasticity, which allows it to stretch and return to its original shape. It is also lightweight and breathable, making it a popular choice for activewear and swimwear. Elastic fiber is also used in medical compression garments, as well as in furniture upholstery and automotive interiors.