| Acronym | Meaning |
| RIR | Reference-intensity Ratio |
| PTS | Phosphotransferase System |
| POSS | Polyhedral Oligomeric Silsesquioxane |
| AFOEHL | Air Force Occupational And Environmental Health Laboratory |
| ISST | International Subcommission On Stratigraphic Terminology |
| TCS | Target Current Spectroscopy |
| UCEPA | Unitary Coupled Electron Pair Approximation |
| AEA-MO | All-electron Approxn.-mol. Orbital |
| SCPA | Single-site Coherent-potential Approximation (for Electronic Structure Calcns.) |
| RI | Refractive Index |