"Sportswear has been called America's main contribution to the history of fashion design, developed to cater to the needs of the increasingly fast-paced lifestyle of American women. It started out as a fashion industry term describing informal and interchangeable separates (i.e., blouses, shirts, skirts and shorts), and in the 1920s became a popular word for relaxed, casual wear typically worn for spectator sports. Since the 1930s the term has been used to describe both day and evening fashions of varying degrees of formality that demonstrate this relaxed approach while remaining appropriate wear for many business or social occasions." - Wikipedia.com