Elastane is a stretchable synthetic fiber that is added to textiles for greater shape retention and fit - usually 2 to 30 % in underwear and clothing.

Elastane fibers are also known under the brand names Lycra, Dorlastan, and Spandex.

Elastane is used wherever textiles have to meet special elasticity criteria (e.g. underwear, socks, sportswear). However, parts of the elastic fiber are also found in other garments such as jeans for reasons of fit or shaping.