Simulation

Simulation verification and validation

Sine wave

Single crystal

Single sideband

Single-atom laser

Single-electron transistor

Single-site catalysts (polymer science)

Sintering

Sinus

Siphonaptera

Siphonophora

Siphonostomatoida

Sipuncula

Siren (acoustics)

Sirenia

Sirius

Sirocco

Sirtuin

Sisal

Sister chromatid cohesion

Size effect on strength (civil engineering)

Skarn

Skeletal system

Skin

Skin disorders

Skin effect (electricity)

Skin friction

Skin friction measurement

Skink

Skunk

Slate

Sleep and dreaming

Sleep disorders

Sleep-dependent memory processing

Slider-crank mechanism

Slime mold

Slip (electricity)

Slip rings

Sloan Digital Sky Survey

Sloan Digital Sky Survey: new instruments and projects

Slope

Sloth

Slow earthquakes

Slow neutron spectroscopy

Small interfering RNA (siRNA)

Small modular reactors

Small satellites

Small warship design

Smallpox

Smart card

Smart grid

Smart metering

Smart net-zero energy buildings

Smart structures

Smart structures and materials

Smith chart

Smithsonite

Smog

Smoke

Snake evolution

Snap ring

Snow

Snow line

Snow surveying

Snowfield and neve

Soap

Soapstone

Social class and poverty

Social hierarchy

Social insects

Social intelligence and the brain in the spotted hyena

Social mammals

Social media

Sociobiology

Soda niter

Sodalite

Sodium

Sodium-vapor lamp

Sofar

Soft body armor

Soft computing

Soft lithography

Software

Software engineering

Software engineering tools

Software metric

Software testing

Software-defined radio

Soil

Soil chemistry

Soil conservation

Soil degradation

Soil ecology

Soil fertility

Soil mechanics

Soil microbiology

Soil sterilization

Sol-gel process

Solanales