| Acronym | Meaning |
| ETD | Enhanced Trickle Down (watershed Acidification Model) |
| PANH | Polycyclic Aromatic Nitrogen Heterocycle |
| SEMPA | Scanning Electron Microscopy With Polarization Analysis |
| PSD | Photon Stimulated Desorption |
| FTC | Federal Trade Commission |
| APT | Atomic Polar Tensor (in Ir Spectra Calcn.) |
| TLFPE | Time-local Fokker-Planck Equation |
| PWO | Plane Wave Orbital |
| CSVC | Computer System Validation Committee |
| NVPA | No-virtual-pair Approxn. |