The Business of Athleisure is currently monitoring the current evolution of the word “athleisure”.
Merriam-Webster will define it as, “casual clothing designed to be worn both for exercising and for general use.”
The New York Times defines it as “an expression of contemporary identity telegraphed to the rest of the world via clothes. It’s fashion.”
Wikipedia also has a page on athleisure too.
For right now we would define athleisure as the cultural and sartorial expression of an active lifestyle.