| Acronym | Meaning |
| RSR | Regular Sinus Rhythym |
| RSV | Respiratory Syncitial Virus |
| RUQ | Right Upper Quadrant |
| RX | Prescription |
| S/S | Signs & Symptoms |
| S/S | Signs & Symptoms |
| SAB | Spontaneous Abortion |
| SABA | Supplied Air Breathing Apparatus |
| SAED | SemiAutomatic External Defibrillator |
| SAST | Serum Aspartate Aminotransferase |
| SB | Spina Bifida |
| SBO | Small Bowel Obstruction |
| SC | Subcutaneous |
| SGPT | Serum Glutamic-pyruvic Transaminase |
| SLE | Systemic Lupus Erythematosus |
| SLUD | Salivation |
| SMO | Standing Medical Orders |
| SNF | Skilled Nursing Facility |
| SOB | Short(ness) Of Breath |
| SR | Sedimentation Rate |
| SS | Social Services |
| ST | Sinus Tachycardia (cardiac) |
| STD | Sexually Transmitted Disease |
| STH | Somatotropic Hormone |
| STM | Short Term Memory |
| SUI | Stress Urinary Incontinence |
| SUI | Stress Urinary Incontinence |
| SVR | Systemic Vascular Resistance |
| SVT | Supra-Ventricular Tachycardia |
| SX | Symptoms |
| SX | Surgery |
| SZ | Seizure |
| T3 | Triiodothyronine |
| T3 | Triiodothyronine |
| T4 | Thyroxine |
| TB | Tuberculosis/Trouble Breathing |
| TBF | Total Body Failure |
| TBI | Traumatic Brain Injury |
| TBSA | Total Body Surface Area |
| TCDB | Turn, Cough, Deep Breathe |
| TED | Thrombo-Embolism Deterrent |
| TED | (hose) Thrombo-embolism Deterrent |
| TEP | Transesophageal Puncture |
| THR | Total Hip Replacement |
| THR | Total Hip Replacement |
| TIA | Transient Ischemic Attack |
| TIBC | Total Iron Binding Capacity |
| TID | Three Times A Day |
| TIL | Tumor Infiltrating Lymphocytes |
| TKR | Total Knee Replacement |