A scuba set is an independent breathing set that provides a scuba diver with the breathing gas necessary to breathe underwater during scuba diving. It is much used for sport diving and some sorts of work diving.

The word SCUBA, acronym for self-contained underwater breathing apparatus, was coined in 1952 by Major Christian Lambertsen who served in the U.S. Army Medical Corps from 1944 to 1946 as a physician. Lambertsen's invention (patented by himself several times from 1940 to 1989) was a rebreather and is not related to the diving regulators and diving cylinders used today. Compressed air-supplied modern regulators, nowadays improperly called SCUBA sets, are a 1943 invention from the Frenchmen Émile Gagnan and Jacques-Yves Cousteau, but in the English language Lambertsen's acronym ended by taking the place of the original Gagnan's and Cousteau's invention name (supposedly to be Aqua-Lung in English, often spelled "aqualung", a name that Cousteau coined for commercialization in all English-speaking countries). As with radar, the acronym SCUBA has become so familiar that it is often not capitalized and is treated as an ordinary noun. For example, it has been taken into the Welsh language as sgwba.