U4, U-4, or U04 may refer to:
Science and technology
- U4 spliceosomal RNA, a non-coding RNA component of the major U2-dependent spliceosome
- Haplogroup U4 (mtDNA), a human genetic group
- U4, unitary group of degree 4
- U-47700, a synthetic opioid
- U04, the ICD-10 code for severe acute respiratory syndrome
Transport
- Underground railways
- U4 (Berlin U-Bahn), a subway line in Berlin, Germany
- U4 (Frankfurt U-Bahn), a subway line in Frankfurt, Germany
- U4, a Hamburg U-Bahn line
- U4, a Munich U-Bahn line
- U4, a Vienna U-Bahn line.
- German submarine U-4, one of several German submarines
- London Buses route U4
- U-4, the U.S. Air Force version of the Aero Commander (aircraft), a light twin-engined aircraft from Aero Design and Engineering Company
- U-4, the Japanese air self-defense force designation for the Gulfstream IV aircraft
- U4, PMTair (former) IATA airline designator
- U4, Buddha Air current IATA airline designator
Organizations
- U4, the former name of the Maple League of Universities
- Anti-Corruption Resource Centre, based at the Chr. Michelsen Institute in Bergen, Norway
Other uses
- U4, an unemployment figure released by the United States Bureau of Labor Statistics
- Ultima IV: Quest of the Avatar, a video game
See also
- 4U (disambiguation)