Many people use the word Jacuzzi to describe a hot tub or spa, but in fact they are incorrect as Jacuzzi is a brand name.
It's just the same as how people use the brand name 'Hoover', to call a vacuum cleaner.
Many people commonly use the word Jacuzzi for any bath tub with jets in. This is because most people have experienced the in ground hot tubs found at hotels, health clubs and on cruise ships which are normally called Jacuzzi's
Tubs
The reason why many people use wrongly the word Jacuzzi is due to the Venturi jet that Roy Jacuzzi invented and patented in 1968.
A Venturi jet is one that induces air into the flow of the water creating the bubbling effect. The ratio of air to water can be adjusted by using an air control.
The hot tubs on today's market have a pump that circulates the water through pipes and then out of underwater Venturi jets. This then creates the bubbling effect within the tub that provides the hydrotherapeutic relaxation which many people enjoy.
It was during the 1900's that the Jacuzzi brothers wanted to help their family member that had an arthritis problem. They invented a portable "hydrotherapy pump", this being a pump that increases the water pressure through a small massage jet.
During the 1960's, Roy Jacuzzi took over the business and then started marketing and selling the first Jacuzzi hot tub using the same jet systems that was invented by this family.
The Jacuzzi brother's patent ran out 10 years later in 1976 which lead to the American hot tub market taking off as they were able to use the Jacuzzi type jets. Hot Tub manufactures have improved the jets to give a better hydrotherapeutic effect.
Since the America Hot Tub market has taken off it has been spreading over to the UK, but within the UK most people will call them Hot Tubs where as people in America use Spa, The only time you will see the word Jacuzzi is when the brand Jacuzzi are are being sold or when they sell Jacuzzi Hot Tub spare parts, but no other company can use name Jacuzzi.
What is a Jacuzzi?