| Acronym | Definition |
|---|
| REX | Regional Express (Australian airline) |
| REX | Request to Exit (security) |
| REX | Readiness Exercise |
| REX | Routine Exercise |
| REX | Rentenindex (German bond index) |
| REX | Regular Expressions for Xml |
| REX | Remote Events for Xml |
| REX | Route Extension |
| REX | Restructured Extended Executor |
| REX | Remote Execution |
| REX | Report Definition |
| REX | Real-Time Executive |
| REX | Receiver/Exciter (Radar Subsystem) |
| REX | Radiation Experiment (studies scintillation effects of the Earth's atmosphere on RF transmissions; first spacecraft to successfully employ GPS navigation) |
| REX | Retour d'Expérience (French) |
| REX | REXX Script (file extension) |
| REX | Real Estate Excellence (awards) |
| REX | Radio Science Experiment (NASA New Horizons Project) |
| REX | Relocatable Executable |
| REX | Remote Events for XML (Extensible Markup Language) |
| REX | Rurtal-Express (Germany) |
| REX | Reynosa, Tamaulipas, Mexico - General Lucio Blanco Airport (Airport Code) |
| REX | Registered Export System (trade) |
| REX | REST-Enabled XHTML |
| REX | Rheintal-Express (Germany) |
| REX | Regional Energetics Experiment |
| REX | Relativistic Electron Beam Experiment |
| REX | Rear Entertainment Xtreme (in-car entertainment system) |
| REX | Remote Interface Unit Exerciser |
| REX | Requisition Exception Code |
| REX | Reflector Erosion Experiment |
| REX | Reliability of Effective Service |