| S | Greek capital letter sigma; syphilis; summation of series |
|---|---|
| s | Greek lower case letter sigma; conductivity; cross section; millisecond; molecular type or bond; pop... |
| SR | sarcoplasmic reticulum; saturation recovery; scanning radiometer; screen; secretion rate; sedimentat... |
| ER | efficiency ratio; epigastric region; ejection rate; electroresection; emergency room; endoplasmic re... |
| RAR | rapidly adapting receptor; rat insulin receptor; retinoic acid receptor; right arm reclining; right ... |