A cadet is a person who is junior in some way. The term is often used by uniformed services.
In the United Kingdom and other Commonwealth countries, a cadet is a member of one of the cadet forces.
In the UK these are: the Combined Cadet Force, the Sea Cadets, Army Cadets and the Air Training Corps.
In the United States, cadet refers to an officer in training. The United States Navy and United States Marine Corps use the term midshipman, while the United States Coast Guard, United States Air Force, and United States Army all indeed use the term cadet. See Officer Cadet for this usage, the term used for an officer in training in the UK. Students at the Military Academy at West Point, the Air Force Academy in Colorado Springs, and the Coast Guard Academy in New London, CT are referred to as "cadets", while students at the Naval Academy in Annapolis are referred to as midshipmen. Members of the ROTC and JROTC programs of the various uniformed services are also titled cadet, as well as members of the Navy League Sea Cadets, Civil Air Patrol Cadet Program, American Cadet Alliance and students at military high schools (e.g., Valley Forge Military Academy).
In Canada, the term "cadet" refers to either an officer in training, with the official rank names as Officer Cadet for the Air Force and Army and Naval Cadet for the Navy. Also, the term Cadet can relate to the subdepartment of the Department of National Defence (DND), the Royal Canadian Cadets movement. This consists of Sea Cadets, Army Cadets and Air Cadets in units across Canada.
In Germany, the rank Cadet (German: Seekadett) only exists in the German Navy for officers in training. In the Army and the Luftwaffe, officers in training usually have the rank of a Fahnenjunker or Ensign (German: Fähnrich) before they are promoted into the rank of a Lieutenant.
In Norway, "cadet" is a pupil of the "Krigsskolen", of the schools of either the Army, the Navy, or to the Air Force educating commanding officers. Today the nco's unfortunately hold their ranks at the Military Academy.
In Ireland, Cadet is a pupil of the Military College, which carries out officer training for the Air Corps, Army and Naval Service. Training takes 2 years and the Cadets are split into Senior and Junior Grades and Classes.
In Australia, a "Cadet" is person aged between 13 and 20 who is a member of the Australian Defence Force Cadets (ADFC). The ADFC is comprised of the Australian Navy Cadets (ANC), the Australian Army Cadets (AAC), and the Australian Air Force Cadets (AAFC).
Similar usage exists in the UK for personnel in training to become fire and rescue service officers.
In Switzerland, cadet (German: Kadett) refers to a participant of the programsof a corps of cadets (German:Kadettenkorps), which are maintained by public schools or private associations. From the late 18th century to the mid of 20th century, the Kadettenkorps used to prepare highschool students for service in the Swiss army. Influenced by the "Turnerbewegung" ('Gym movement'), the Kadettenkorps started in the early 20th century to shift their programm towards sports. Nowadays, the Swiss Cadets Association (German: Kadetten Schweiz) includes Kadettenkorps offering the following programms: general sports (including the national league handball club Kadetten Schaffhausen), trecking (like scouting), march music bands (German:Kadettenmusik) and traffic regulation (German:Verkehrskadetten). Kadettenkorps offering traffic regulation only, are represented by the Swiss Verkehrskadetten Association (German:Schweizerischer Verkehrskadetten Verband).
Some sports teams also refer to players that are in the process of being built up to play for the team at a later date as cadets. Such players often play for a lesser team in the same club. This is done quite commonly in the National Rugby League (NRL).
In Australia, the term is also used to describe a person pursuing a career as a Chartered Accountant under the "Cadetship" program, designed to accelerate career progression for motivated students. The programs are offered to students finishing high school or currently undertaking tertiary studies in relevant courses by several Accounting firms such as Three of the Big 4 accountancy firms (KPMG, PricewaterhouseCoopers and Ernst & Young), and mid-tier firms such as BDO and Grant Thornton.
To refer to someone as a space cadet is to imply that they are "on another planet", i.e. foolish or dim. For example; "That guy is cadetting it."
Cadet may also refer to someone belonging to "The Cadets" a Division I Drum and Bugle Corps, who have been Drum Corps International World Champions numerous times and currently hold that position.