| SI | International System of Units [Fr. le Systeme International d'Unites]; sacroiliac; saline infusion; ... |
|---|---|
| SOI | severity of illness |
| SSLI | serum sickness-like illness |
| TIS | tetracycline-induced steatosis; transdermal infusion system; triage illness scale; trypsin-insoluble... |
| UCI | unusual childhood illness; urethral catheter in; urinary catheter in |