| SFD | silo filler's disease; skin-film distance; small for dates; spectral frequency distribution |
|---|---|
| SGA | small for gestational age |
| SI | International System of Units [Fr. le Systeme International d'Unites]; sacroiliac; saline infusion; ... |
| SIG | small inducible gene |
| SISS | Sentinel Injury Surveillance System [for Gunshot and Stab Wounds] small inducible secreted substance... |