A crop top is a top that exposes the waist, or stomach
Sale, Home Office, Activewear
The crop top started gaining prominence in the fashion industry during the 1930s and 1940s — the latter in particular due to fabric rationing in World War II — it was largely confined to swimwear at the time.
In the 1980s, cutoff crop tops became more common as part of the aerobics craze and as a result of the popularity of the movie Flashdance. Singer Madonna wore a mesh crop top in her music video for the song "Lucky Star". In the 2010s, the crop top experienced a revival due to the popularity of 1990s retro fashion.