| Acronym | Meaning |
| RPP | Reverse Pulse Polarography |
| PARS | Photoacoustic Raman Spectroscopy |
| PRTD | Proportional Residence Time Distribution (of Liquid Streams In Equalization Basins In WWT) |
| SAFM | Scanning Attractive Force Microscopy |
| SDD | Silicon Drift Detector |
| SFCCCC | Space-fixed Complex-coordinate Coupled-channel Method |
| SCM | Shell-correction Method (in Calcns. For Metal Clusters) |
| SCI | Single Excitation Configuration Interaction |
| CGTO | Contracted Gaussian-type Orbital |
| APCA | Air Pollution Control Association |