- rotating fluids
- rotating prism
- rotational wave
- rotatory power
- rough-plane
- rough-polish
- rolling bearing
- rolling resistance
- rotary
- rotary magazine
- rotating annulus
- rotating evaporator
- safe concentration
- safelight filter
- safety report
- rowland circle
- rowland mounting
- rubber buld
- rumble
- Rutherford scattering
- sabine coefficient
- safety container
- safety placard
- safety zone
- rotating process
- salting agent
- saltpeter process
- saltpetre process
- samarium effect
- sample changer
- safety catch
- safety funnel
- safety tank
- safety tube
- sampling pump
- saturated boiling
- saturation concentration
- saturation point
- scanning spectrometer
- scattered radiation
- Schwarzschild radius
- scorched
- sand bath
- scanning laser
- scope
- scram delay
- screening number
- scattered neutron
- Schottky noise
- Schrodinger equation
- scalding
- scattered energy
- scattering foil
- scattering matrix
- scattering source
- Schmidt number
- schuilingite
- scintillation counter
- scintillation spectrometer
- scram control
- screw valve
- seal assembly
- sealed source
- screen
- screen constant
- screen factor
- screen holder
- screw joint
- seal gas
- seal unit
- seasonal fluctuations
- seasonal variation
- secondary
- secondary discharge
- secondary particle
- secondary process
- sedimentation coefficient
- sedimentation effect
- selection rule
- self-induction
- self-repair
- self-replication
- secondary ionization
- secondary reactor
- secondary separation
- secondary side
- secondary standard
- section enlargement
- sectioning technique
- secular equation
- secular equilibrium
- seethe
- selective reducer
- self-assembler
- self-induced
- self-timer
- semi-conductor
- semiconductor doping
- semireflecting plate
- self-flux