the.com/tracksuit

means A matching two-piece set of loose jacket and pants, designed for athletes to wear while warming up or cooling down — and adopted by everyone else for maximum comfort with minimum effort.

from Straightforward compound of 'track' (the running track, the athletic sense that goes back to the 1800s) and 'suit' (a matched set of clothes). The garment itself emerged in the 20th century as sportswear worn to and from the actual exercise — loose, zippable, easy to peel off before a race. The irony of its name was baked in early: it was always more honestly a 'sitting around near the track' suit than a running one.