China 
Africa 
- Strictureplasty
- Strictures
- Stridor
- Strimvelis
- String sign
- Stringent response
- Stroboscope
- Stroke
- Stroke Belt
- Stroke recovery
- Stroke volume
- Stroma
- Stromal
- Stromal cell-derived factor 1
- Stromal cells
- Stromal tumor
- Stromatolites
- Strong Heart Study
- Strong reciprocity
- Strongyloides
- Strongyloides stercoralis
- Strongyloidiasis
- Strontium
- Strontium 90
- Strontium chloride
- Strontium-89
- Stroop effect
- Stroop task
- Stroop test
- Structural alignment
- Structural analogs
- Structural biology
- Structural family therapy
- Structural genes
- Structural genomics
- Structural heart disease
- Structural proteins
- Structural variation
- Structure activity relationship
- Structure elucidation
- Structure-based drug design
- Structured Clinical Interview for DSM
- Structured Inventory of Malingered Symptomatology
- Structured light plethysmography
- Struma ovarii
- Struvite
- Strychnine
- Strychnine poisoning
- Strychnos nux vomica
- Student engagement
- Studentized residuals
- Study 329
- Study heterogeneity
- Study of Tamoxifen and Raloxifene
- Stunted growth
- Stupor
- Sturge-Weber syndrome
- Stuttering
- Stuttering therapy
- Stye
- Styloglossus
- Stylohyoid ligament
- Stylohyoid muscle
- Styloid process
- Stylomandibular ligament
- Stylomastoid artery
- Stylomastoid foramen
- Stylopharyngeus muscle
- Styrax
- Styrene
- Styrene butadiene styrene
- Styrene oxide
- Sub-replacement fertility
- Subacromial bursa
- Subacromial bursitis
- Subacute combined degeneration of spinal cord
- Subacute cutaneous lupus erythematosus
- Subacute sclerosing panencephalitis
- Subacute thyroiditis
- Subarachnoid cistern
- Subarachnoid cisterns
- Subarachnoid hemorrhage
- Subarachnoid space
- Subarcuate fossa
- Subcallosal area
- Subcallosal gyrus
- Subcellular localization
- Subchondral bone
- Subclades
- Subclavian artery
- Subclavian steal syndrome
- Subclavian vein
- Subclavius
- Subclavius muscle
- Subclinical hyperthyroidism
- Subclinical hypothyroidism
- Subclinical infections
- Subclinical seizures
- Subcloning
- Subcommissural organ
- Subconjunctival hemorrhage
- Subconjunctival injection
- Subcoracoid bursa
- Subcorneal pustular dermatosis
- Subcortex
- Subcortical dementia
- Subcostal nerve
- Subcostal plane
- Subcutaneous
- Subcutaneous emphysema
- Subcutaneous fat
- Subcutaneous implant
- Subcutaneous injection
- Subcutaneous mastectomy
- Subcutaneous tissue
- Subdermal implant
- Subdural effusion
- Subdural empyema
- Subdural hematoma
- Subdural hygroma
- Subdural space
- Subependymal giant cell astrocytoma
- Subependymal zone
- Subependymoma
- Subepithelial connective tissue graft
- Subfertility
- Subfornical organ
- Subgaleal hemorrhage
- Subgenomic mRNA
- Subglottic
- Subglottic stenosis
- Subgranular zone
- Subgroup analysis
- Subiculum
- Subinvolution
- Subitizing
- Subjective Units of Distress Scale
- Subjective character of experience
- Subjective refraction
- Subjective units of distress scale
- Subjective well-being
- Subjectivity
- Sublimation
- Sublingual
- Sublingual administration
- Sublingual gland
- Sublingual space
- Subluxations
- Submandibular duct
- Submandibular gland