Spandex
From Longman Dictionary of Contemporary EnglishSpandexSpan‧dex /ˈspændeks/ noun [uncountable] trademark a material that stretches, used especially for making tight-fitting sports clothesExamples from the CorpusSpandex• He said Nicole Simpson did not own the gold Spandex leotard described by the clinic employee.• The leotard she wore was a pale yellow Spandex, defining the wide shoulders and lean hips of a gymnast.