Seismology is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other planet-like bodies.

Seismic tomography is a technique for imaging the subsurface of the Earth with seismic waves produced by earthquakes or explosions.

A seismic source is a device that generates controlled seismic energy used to perform both reflection and refraction seismic surveys.

The Seebeck effect is the electromotive force (emf) that develops across two points of an electrically conducting material when there is a temperature difference between them.

Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at the Earth's surface, followed by cementation.

Secondary energy is a carrier of energy, such as electricity.

Some plants have a secondary containment system that encompasses the primary system.

A secondary cell is a type of electrical battery which can be charged, discharged into a load, and recharged many times.

Second generation biofuels, also known as advanced biofuels, are fuels that can be manufactured from various types of non-food biomass such as plant materials and animal waste. Second generation feedstocks include lignocellulosic biomass or woody crops, agricultural residues or waste, as well as dedicated non-food energy crops.

The second (symbol: s, abbreviation: sec) is the base unit of time in the International System of Units (SI).

The storage of heat or cold for use at a later time when either may not be available if required quantities.

Mean sea level is an average level of the surface of one or more of Earth's bodies of water from which heights such as elevation may be measured.

A sea breeze or onshore breeze is any wind that blows from a large body of water toward or onto a landmass; it develops due to differences in air pressure created by the differing heat capacities of water and dry land.

Scrubber systems are a diverse group of air pollution control devices that can be used to remove some particulates and/or gases from industrial exhaust streams.

A screw pump is a more complicated type of rotary pump that uses two or three screws with opposing thread — e.g., one screw turns clockwise and the other counterclockwise.

A scram is an emergency shutdown of a nuclear reactor effected by immediately terminating the fission reaction.

A Scott-T transformer (also called a Scott connection) is a type of circuit used to produce two-phase electric power from a three-phase source, or vice versa.

Scope statements can take many forms depending on the type of project being implemented and the nature of the organization.

Scope creep in project management refers to changes, continuous or uncontrolled growth in a project’s scope, at any point after the project begins. This can occur when the scope of a project is not properly defined, documented, or controlled.

Scope is the defined features and functions of a product, or the scope of work needed to finish a project.