| Somatotypes |
| Somites |
| Somnambulism |
| Son of Sevenless Protein, Drosophila |
| Son of Sevenless Proteins |
| Sonchus |
| Songbirds |
| Sophora |
| Sorbic Acid |
| Sorbitol |
| Sorbus |
| Sordariales |
| Sorghum |
| Sorption Detoxification |
| SOS Response (Genetics) |
| SOS1 Protein |
| Sotalol |
| Sound Localization |
| Sound Spectrography |
| South Africa |
| South Australia |
| Southeastern United States |
| Southwestern United States |
| Soy Foods |
| Soy Milk |
| Soybean Oil |
| Soybean Proteins |
| Soybeans |
| Sp Transcription Factors |
| Sp1 Transcription Factor |
| Sp2 Transcription Factor |
| Sp3 Transcription Factor |
| Sp4 Transcription Factor |
| Space Flight |
| Space Motion Sickness |
| Space Perception |
| Space Simulation |
| Space Suits |
| Space-Time Clustering |
| Spacecraft |
| Spalax |
| Spanish-American War, 1898 |
| Sparganosis |
| Sparganum |
| Sparrows |
| Sparsomycin |
| Sparteine |
| Spartium |
| Spasm |
| Spasms, Infantile |
| Spastic Paraplegia, Hereditary |
| Spatial Behavior |
| Specialism |
| Specialties, Dental |
| Specialties, Medical |
| Specialties, Nursing |
| Specialties, Surgical |
| Specialty Boards |
| Specialty Uses of Chemicals |
| Species Specificity |
| Specific Pathogen-Free Organisms |
| Specimen Handling |
| Spectinomycin |
| Spectral Karyotyping |
| Spectrin |
| Spectrometry, Fluorescence |
| Spectrometry, Gamma |
| Spectrometry, Mass, Electrospray Ionization |
| Spectrometry, Mass, Fast Atom Bombardment |
| Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization |
| Spectrometry, Mass, Secondary Ion |
| Spectrometry, X-Ray Emission |
| Spectrophotometry |
| Spectrophotometry, Atomic |
| Spectrophotometry, Infrared |
| Spectrophotometry, Ultraviolet |
| Spectroscopy, Electron Energy-Loss |
| Spectroscopy, Fourier Transform Infrared |
| Spectroscopy, Mossbauer |
| Spectroscopy, Near-Infrared |
| Spectrum Analysis |
| Spectrum Analysis, Mass |
| Spectrum Analysis, Raman |
| Speech |
| Speech Acoustics |
| Speech Articulation Tests |
| Speech Discrimination Tests |
| Speech Disorders |
| Speech Intelligibility |
| Speech Perception |