DET or Det may refer to:
Education
- Department of Education (New South Wales), formerly Department of Education and Training
- Duolingo English Test (DET), a standardized language test
Mathematics
- Detection error tradeoff
- det, mathematical notation for the determinant of a matrix
Places
- Detroit, Michigan, United States
- Detroit (Amtrak station)
- Coleman A. Young International Airport, Detroit (IATA:<code>DET</code>)
Sport
- Sports in Detroit, US
- Detroit Lions, National Football League
- Detroit Pistons, National Basketball Association
- Detroit Tigers, Major League Baseball
- Detroit Red Wings, National Hockey League
Other uses
- Dafydd Elis-Thomas (1946-2025), Welsh politician
- Determiner, in interlinear glossing
- Diethyltryptamine, a psychedelic drug
- It (poetry collection), 1969, by Inger Christensen ()
- 14 Intelligence Company "The Det", a British undercover military unit