sportswear means: This term was originally used to describe clothing meant for active sport, but later it also applied to clothes worn to view sporting events. However, the general category of casual wear has been expanded to include all types of casual wear that can be worn anytime of day for many different activities. Activewear today is often used to refer to active sport clothing. Many consider sportswear to have made a significant contribution to American clothing design. (in Fashion Dictionary)
What else does sportswear mean?
Comfortable and casual clothing. (in Merlin Dictionary)
Casually dressed clothes that can be worn for business and social events. (in Merlin Dictionary)