| Acronym | Meaning |
| APEX | Acquisition Planning and Execution |
| APEX | Adaptive Planning and Execution (US DoD) |
| APEX | Advanced Prototyping, Engineering & eXperimentation (US Army Modeling and Simulation Laboratory - Redstone Arsenal, AL) |
| APEX | Aerodynamic Performance Experiment |
| APEX | APLE Prototype Experiment |
| APEX | Arctic Pulse Experimental (Sonar) |
| APEX | Argonne Production, Expansion and Exchange (model for electrical systems) |
| APEX | Armor Piercing Explosive (ammunition type) |
| APEX | Automated Power Expert |