Scuba set
A scuba set is an independent breathing set that provides a scuba diver with the breathing gas
Breathing gas
Breathing gas is a mixture of gaseous chemical elements and compounds used for respiration.Air is the most common and only natural breathing gas...

 necessary to breathe underwater during scuba diving
Scuba diving
Scuba diving is a form of underwater diving in which a diver uses a scuba set to breathe underwater....

. 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
Major (United States)
In the United States Army, Air Force, and Marine Corps, major is a field grade military officer rank just above the rank of captain and just below the rank of lieutenant colonel...

 Christian Lambertsen
Christian J. Lambertsen
Christian James Lambertsen was an American environmental medicine and diving medicine specialist who was principally responsible for developing the United States Navy frogmen's rebreathers in the early 1940s for underwater warfare...

 who served in the U.S. Army Medical Corps from 1944 to 1946 as a physician.