| Acronym | Meaning |
| MWOA | Mount Wilson Observatory Association |
| PR | Public Relations -Puerto Rico (postal Symbol; ISO 3166 Digram) |
| PAWS | Phased Array Warning System - Progressive Animal Welfare Society |
| ERI | Eritrea (ISO 3166 Trigram) |
| YEM | Yemen (ISO 3166 Trigram) - Manitowaning/Manitoulin East Municipal Airport IATA Airport Code |
| MEMS | Microelectromechanical System |
| IISS | International Institute For Strategic Studies |
| R2I | Resistance To Interrogation |
| LSD | Landing Ship |
| DSWA | (U.S.) Defense Special Weapons Agency |