| X-OFF | Transmitter OFF 
| Others |
| X-ON | Transmit ON
| Others |
| X-ON | Transmitter ON
| Others |
| X-POST | Crosspost
| Others |
| X-PV | Extra Purpose Vehicle
| Others |
| X-RAY | Named X-radiation to signify an unknown type of radiation by its discoverer Wilhelm Rontgen.
| Others |
| X-SCID | X-linked Severe Combined Immunodeficiency Disorder
| Others |
| X-SP | eXtreme SPort
| Others |
| X-TASS | XML Trust Assertion Service Specification
| Others |
| X.X | Exasperated, irritated, annoyed
| Others |
| X/OPEN | X/Open Company, LTD.
| Others |
| X/XOD | Xanthine and Xanthine Oxidase
| Others |
| X01 | Paradox Secondary Index
| Others |
| X10 | X Window dump Bitmap graphics
| Others |
| X11 | X Windows System, Version 11
| Others |
| X11R6 | X Windows System, Version 11 Release 6
| Others |
| X20 | Hexadecimal to octal
| Others |
| X21 | Arthur Dunn Air Park Airport, Titusville, Florida USA
| Others |
| X22 | Bell X-22, an American experimental tilt-fan aircraft of the 1960s.
| Others |
| X22 | Clathrin Heavy Chain Monoclonal Antibody
| Others |
| X22 | Paul Magriel, American professional backgammon player.
| Others |
| X2B | Hexadecimal to Binary
| Others |
| X2C | Anything to Car
| Others |
| X2C | Hexadecimal to Character
| Others |
| X2D | Anything to Dvd
| Others |
| X2D | Hexadecimal to Decimal
| Others |
| X2V | Anything to Vehicle
| Others |
| X2V | X to Vehicle
| Others |
| X2X | Anything to Anything
| Others |
| X2X | Xcom to Excel
| Others |
| X3D | Extensible Three Dimensional
| Others |
| X3D | Extensible Three-Dimensional
| Others |
| X3D | Next Generation Three Dimensional
| Others |
| X3D | x3d and xdart Formats
| Others |
| X3MC | X-Drive Three Series Motorsport Competition
| Others |
| X4L | Exchange for Learning
| Others |
| X5MC | X-Drive Five Series Motorsport Competition
| Others |
| x64 | 64-bit version of the x86 instruction set
| Others |
| X6P | Xr V6 Premium
| Others |
| x86 | Generic name for Intel processors released after the original 8086 processor
| Others |
| XA | CD-ROM extended architecture
| Others |
| XA | Chi Alpha
| Others |
| XA | Chi Alpha Campus Ministries
| Others |
| XA | Experiential Agency
| Others |
| XA | Experimental Agency
| Others |
| XA | eXtended Architecture
| Others |
| XA | The Sims - Electronic Arts
| Others |
| XA | X Acse
| Others |
| XA | XA audio
| Others |
| XA | Xopen Architecture
| Others |