The synthetic fiber spandex was discovered by DuPont chemist Joseph C. Shivers. The original material was called Fiber K, and later, DuPont trademarked the name Lycra to distinguish their particular blend.
The general product, however, has long been called spandex. The fabric was named such precisely because of what it does. Spandex is an anagram, a shuffling of a word’s letters to create a new word, out of the word “expands”.
Interestingly enough, the term “spandex” only caught on in the land of its invention: North America. Elsewhere in the world, the fiber is referred to most frequently as “elastane” (or variants thereof), still alluding to the extreme elasticity of the material.