- surface moisture
- surface noise
- surface passivation
- surface physics
- surface protection
- surface refrigeration
- surface resistance
- surface scattering
- surge
- surge absorber
- surge chamber
- surge current
- surge drum
- surge generator
- surge header
- subsynchronous
- succinite
- suction duct
- suction filter
- suction pyrometer
- suction riser
- suction vapour
- suffix notation
- sulfating
- summation
- superachromatic lens
- superatmospheric pressure
- superconducting device
- superconducting layer
- superconduction current
- supercooled vapour
- supercritical
- superexcitation
- superficial
- superficial density
- superficial freezing
- superfine
- superfluid
- superfluid helium
- superfluidity
- superfreeze door
- supergiant star
- supergravity
- superheat
- superheat coil
- superheat control
- superheat curve
- superheat region
- superheat removal
- superheated condition
- superheated refrigerant
- superheated vapour
- superheating
- superheating cycle
- superheavy quasimolecule
- superheterodyne
- superinsulation
- surge receiver
- surge tank
- surge test
- surging characteristic
- surrounding air
- surrounding area
- surrounding atmosphere
- susceptance standard
- susceptibility
- suspended ceiling
- suspended transformation
- sustained sound
- swallowtail catastrophe
- swan-neck
- sweat cooling
- sweating
- sweep generator
- swept volume
- swift diffuser
- swing
- swinging reactor
- swirl diffuser
- swirling motion
- switch
- switch bay
- switch board
- swinging choke
- swinging quartz
- switch pretravel
- switch train
- switching diode
- switching reactor
- switching transistor
- symmetric pair
- symmetric space
- symmetry law
- synchro resolver
- synchro system
- synchrocyclotron
- synchronizing current
- synchronoscope
- synchronous capacitor
- synchronous inverter