A Jacuzzi bathtub is nominally any bathtub made by the Jacuzzi corporation. In common use, however, often the word "Jacuzzi" is used to refer to any bathtub having adjustable jets that constantly agitate the water.
In 1956, the Jacuzzi corporation in Italy invented an innovative pumping system that enabled the construction of purpose-built hydrotherapy baths featuring water jets. As it was the first company to bring these products to the market, its name and "Jacuzzi" trademark became synonymous with these kinds of baths. Later in the 1970s, the company released hot-tub baths that featured not only water jets but also internal heating systems, and hence the word "Jacuzzi" is commonly used to describe such bath systems.