Consists of two or more parts that form a portion of an assembly or a unit.
Smaller than the atom. The structure of the atom.
Subatomic Erosion
A process in which structures on an integrated circuit′s substrate are eroded by the flow of electrons in much the same way as land is eroded by a river.
Subatomic Particle
Any particle that is small compared to the size of the atom.
A separate analog or digital signal carried on a main radio transmission, which may carry extra information such as voice or data.
A chain reaction that dies out because an average of less than one neutron from each fission reaction causes another fission reaction.
Rough or structural floor placed directly on the floor joists or beams to which the finished floor is applied.
A subset H of a group G is a subgroup (of G) provided it′s a group with respect to the group operation of G.
Sinusoidal quantity of a frequency that is an integral submultiple of a fundamental frequency.
A list of all the subjects in the Science and Engineering Encyclopaedia
Solid or concrete products of sublimation. Not powder.
The transition of a substance directly from the solid phase to the vapour phase, or in reverse, without going through the liquid phase.
Submersible Pump
A pump that operates only when totally submersed in the fluid which is being pumped.
Submillimeter Wave
The portion of the electromagnetic spectrum between 300 GHz and 1 THz, also known as microwave.
Subnet Mask
The part of the address mask that identifies an individual network within a larger network.
A previously known algorithm used in another algorithm.
A subset of a given set is a collection of things that belong to the original set.
A set of electrons with the same azimuthal quantum number.
Having a speed less than that of sound in a designated medium.
A subset W of Rn is a subspace of Rn if….
Material objects that can undergo various transformations related to artificial or natural phenomena.
Substitution Reaction
A reaction in which an atom or fragment within a molecule is replaced with another.
The underlying or base material.
Component of a vibration signal that has a frequency less than shaft rotation frequency.
Also called a subharmonic.
The binary operation of finding the difference between two quantities.
A number that is to be subtracted from another number.
A speaker designed exclusively for low-frequency reproduction.
Successive Approximation Register
Uses a digital-to-analog converter to determine the output word successively, bit by bit.
Suckdown Wind Tunnel
The inlet is open to atmosphere and the fan is placed after the test section.
Suction Filter
A pump intake-line filter in which the fluid is below atmospheric pressure.
Suction Stroke
Another name for the air intake stroke on an internal combustion engine.
Suction Valve
An automatic non-return valve, which opens when the boiler is at less than atmospheric pressure.
Sugars are a group of carbohydrates, soluble in water and having a sweet taste.
Abbreviation of Super Ultra-Low Emission Vehicle.
A compound containing the SO42- ion.
A compound containing the SO32- ion.
A non-metallic element occurring in several allotropic forms.
Sulphur Dioxide
A colourless gas formed when sulphur is burnt in air and forms sulphurous acid when dissolved in water.
Sulphur Hexafluoride


A colourless, non-toxic and non-flammable gas at room temperature and pressure.

Sulphur Monoxide


Only found as a dilute gas phase. When concentrated or condensed, it converts to S2O2 (disulphur dioxide).

Sulphur Trioxide


In the gaseous form, this species is a significant pollutant, being the primary agent in acid rain.

Sulphuric Acid


An oily, corrosive liquid that acts as a strong acid when dissolved in water.

Sulphurous Acid


A colourless liquid that acts as a weak acid when dissolved in water.

The result of the addition of numbers.
Summary Statistics
A single number representation of the characteristics of a set of data. Usually given by measures of central tendency and measures of dispersion.
Summation Layer Amount
The amount of sky cover for each layer is given in eighths of sky cover attributable to clouds or obscurations.
Summing Network
A combination of two or more parallel resistors used in servosystems as an error detector.
The engine oil reservoir.
The star at the centre of our solar system.
Sun Protection Factor
A rating for lotions used to protect the skin against sunburn.
A device for telling time of day by the shadow which sunlight produces on the instrument.
An area on the surface of the sun marked by a lower temperature than its surroundings and that has magnetic activity.
Super Beryllia
Alternative name for Beryllium Oxide.
Super Cooling
The cooling of a liquid below its freezing temperature without the formation of the solid phase.
Super Glue
More formally known as Cyanoacrylate.
Super Heated Steam
Steam heated above its saturation temperature.
Super Heating
The heating of a liquid above its boiling temperature without the formation of the gaseous phase.
Super High Frequency
Radio Frequencies between 3 GHz and 30 GHz.
Super Ultra-Low Emission Vehicle
A level of standards for tailpipe emissions.
An air compressor used to force more air into an engine than it can inhale on its own.
A cluster of clusters of galaxies which stretches for hundreds of millions of light years.
A general term used to describe the fastest available mainframe computers.
Superconducting Magnets
An electromagnet whose coils are made of a type II superconductor with a high transition temperature and extremely high critical field.
The phenomena by which, at sufficiently low temperatures, a conductor can conduct charge with zero resistance.
Liquids at temperatures below their normal freezing points are said to be "supercooled".
A chain reaction that grows rapidly because an average of more than one neutron from each fission reaction causes another fission reaction.
Supercritical Fluid
A fluid state that occurs when the pressure and temperature exceed the substance′s critical pressure and critical temperature.
Superficial Rockwell Hardness Test
Form of Rockwell hardness test using relatively light loads which produce minimum penetration.
The phenomena by which, at sufficiently low temperatures, a fluid can flow with zero viscosity.
A star with a higher luminosity and a larger radius than a giant of the same spectral classification.
Superheated Vapour
Vapour at a temperature which is higher than the saturation temperature at the existing pressure.
Superheterodyne Receiver
A type of receiver that uses a mixer to convert the RF echo to an IF signal for amplification.
Superior Vena Cava
A large vein that carries oxygen-poor blood to the right atrium from the upper parts of the body.
The death explosion of a massive star, resulting in a sharp increase in brightness followed by a gradual fading.
A binary compound containing oxygen in the -½ oxidation state.
The combining of two or more waves at a location in space.
Supersaturated Solution
A solution that has a concentration of solute that is higher than its solubility.
Numbers or letters written above and to the right of other numbers or letters or symbols indicating how many times the latter is to be used as a factor.
Having a speed greater than the speed of sound in a given medium, especially air.
Supervised Learning
Organization and training of a neural network by a combination of repeated presentation of patterns and required knowledge.
Supplementary Angles
Two angles are supplementary if they add up to 180°.
Supply Voltage
The voltage obtained from the power supply to operate a circuit.
A support contributes to keeping a structure in place by restraining one or more degrees of freedom.
Supporting Electrolyte
An electrolyte added to the solution for the sole purpose to increase the solution conductivity, while the electrolyte does not take part in any reactions.
Elimination or reduction of any component of an emission, as a particular frequency or group of frequencies, in an audio or radio-frequency signal.
Used in mathematics to describe an irrational quantity.
Surface Area
The total area of the surface of a solid.
Surface Combustion
A method of causing a mixture of air and gas to burn by bringing it into contact with a suitable porous surface.
Surface Contour
The outline or profile of a surface.
Surface Filter Media
Porous materials which primarily retain contaminants on the influent face, performing the actual process of filtration.
Surface Filtration
Filtration which primarily retains contaminant on the influent surface.
Surface Finishing
A range of industrial processes that alter the surface of a manufactured item to achieve a certain property.
Surface Force
A force applied to the surface of an object.
Surface Gap Spark Plug
A type of spark plug in which the spark is fired across the insulator surface between the centre electrode and the shell.
Surface Gauge
A gauge used to check the accuracy, of plane surfaces, to scribe lines at desired distances from a given surface and to check the height of a point or points on a piece of work from a given surface.
Surface Insulation Resistance
The electrical resistance of an insulating material between a pair of contacts or conductors.
Surface Mount Hinge
Both leaves secured to the surface of the door and frame.
Surface Mount Technology
The technology used when components are mounted to the surface of circuit boards.
Surface Plasmon
A collective motion of electrons in the surface of a metal conductor, excited by the impact of light of appropriate wavelength at a particular angle.
Surface Roughness
At a microscopic scale, no surface appears perfectly smooth.
Surface Roughness Measurement
There are many different measurement techniques for measuring surface roughness and these are first broken into 4 main categories.
Surface Tension
Small droplets or bubbles of one fluid immersed in another fluid have a spherical shape because of the interfacial tension, or surface tension, between the two fluids.
Surface Water
Rainwater collected and running on the surface of the land rather than being confined to drains and water courses.
Surface-Ignition Engine
Another name for a Semi Diesel Engine.
A material that spreads along a surface, changing the properties of the surface.
A momentary rise of pressure in a circuit.
Surge Protector
A device for protecting electronic equipment from damaging voltage levels sometimes occurring in electrical transients.
In thermodynamics, the surroundings refer to the universe outside the system.
A branch of applied mathematics, including geometry and trigonometry, that aids in determining and delineating the form, extent, and position of the land.
Surveyor′s Wheel
A device for measuring distance.
Abbreviation of Saybolt Universal Seconds which is another name for Saybolt Universal Viscosity.
Suspended Deck
A roadway or railway that hangs from cables slung over towers or from the underside of an arch.
A system consisting of small particles dispersed in a liquid. The system of springs, links and absorbers that suspends a vehicle above its wheels.
Suspension Bridge
A bridge in which the roadway deck is suspended from cables that pass over two towers.
Suspension Bush
Provides compliance and damping between two points of a suspension system.
Sustainer Engine
A rocket engine that maintains the velocity of a rocket vehicle once it has achieved its programmed velocity by use of booster or other engine.
Abbreviation of Saybolt Universal Viscosity.