| Acronym | Meaning |
| RA | Rain (METAR Code) -Rear Area - Reinforced Alert - Republican Army - Right Ascension - Royal Artillery (UK) - Royal Academy |
| C4ISR OR C?ISR | Command |
| G20 | Group Of 20 (G8 + Argentina |
| BSOD | Blue Screen Of Death (distinct From BSD) |
| PPCLI | Princess Patricia's Canadian Light Infantry (regiment) |
| MADD | Mothers Against Drunk Driving - MyoAdenylate Deaminase Deficiency -Multiply-Add |
| IG | Inspector General |
| AMS | Agriculture Marketing Service - American Mathematical Society |
| RPA | Regional Plan Association |
| LR | Lawrencium |