| PSIL | preferred frequency speech interference level |
|---|---|
| RFI | radiofrequency interference; recurrence-free interval; renal failure index |
| RI | radiation intensity; radioactive isotope; radioimmunology; recession index; recombinant inbred [stra... |
| SIL | soluble interleukin; speech interference level |
| SQUID | superconducting quantum interference device |