4D
- 4-D (The X-Files)
- 4-D (psychedelic)
- 4-Digits
- 4D (album)
- 4D (software)
- 4D (train)
- 4D Audio Recording system
- 4D BIM
- 4D Inc
- 4D SAS
- 4D film
- 4D printing
- 4DTV
- 4DX
- Aftermathematics
- Air Sinai
- Alien (Northlane album)
- Cinema 4D
- D4 (disambiguation)
- DDDD (disambiguation)
- Four Dimensions (disambiguation)
- Four-dimensional space
- Fourth dimension (disambiguation)
- Northlane
- Photo print sizes
- Potez 4D
- Revenge of the Cybermen
- Ring finger
- SGI IRIS 4D
- Selective Service System