- subcooled gas
- subcooling coil
- subcritical pressure
- subdivided capacitor
- subdwarf star
- subfreezing area
- sublevel
- sublimation front
- sublimation pressure
- submaster controller
- subrefraction
- subscriber loop
- subsonic
- subsonic compressor
- subsonic velocity
- substance
- substandard instrument
- suction noise
- sum rule
- summer solstice
- sump heater
- sunbeam test
- sunlamp
- sunrise
- sunspot
- super-cooled
- superclusters
- superconduction
- superconductivity
- supercooled fluid
- supercritical extraction
- supercritical state
- superdense star
- superfluid transition
- supergalaxy
- superheat area
- superheat conditions
- superheat stability
- superheated gas
- superheater
- superlattice
- superleak
- superlow temperature
- supermastergroup
- supermultiplet
- supernova remnants
- superparamagnetism
- superposition
- superposition fringe
- superposition theorem
- superpower
- superproton
- superrefractory
- superregeneration
- supersaturated air
- supersaturated solution
- supersensitive relay
- supersoluble
- supersonic
- supersonic aerodynamics
- supersonic compressor
- supersonic diffuser
- supersonic velocity
- superstring
- superstructure
- supersymmetry
- supervisor position
- supervisory control
- supervoltage
- supplementary anode
- supplementary charge
- supplementary tariff
- supply adjustment
- supply agreement
- supply air
- supply control
- supply duct
- supply grille
- supply line
- supply undertaking
- supply voltage
- support
- supporting
- suppressor
- surcharge
- surd
- surface absorption
- surface barrier
- surface boiling
- surface charge
- surface condenser
- surface condition
- surface cooling
- surface current
- surface density
- surface desiccation
- surface element
- surface freezing
- surface integral
- surface leakage