| Rf | respiratory frequency; rutherfordium |
|---|---|
| SFD | silo filler's disease; skin-film distance; small for dates; spectral frequency distribution |
| SSCF | sleep stage change frequency |
| TF | free thyroxine; tactile fremitus; tail flick [reflex]; temperature factor; testicular feminization; ... |
| UF | film unsharpness; ultrafiltrate; ultrafiltration; ultrafine; ultrasonic frequency; universal feeder;... |