| SFD | silo filler's disease; skin-film distance; small for dates; spectral frequency distribution |
|---|---|
| STD | selective T-cell defect; sexually transmitted disease; skin-to-tumor distance; skin test dose; sodiu... |
| TSD | target-skin distance; Tay-Sachs disease; theory of signal detectability |
| VFID | virtual focus-isocenter-distance |