- software testing
- software useful degree
- sojourn time
- Sokhozki formula
- Sokhozki theorem
- solar active region
- solar activity
- solar calendar
- solar constant
- solar corona
- solar flare
- solar magnetic field
- solar motion
- solar neutrino
- solar oscillation
- solar parallax
- solar physics
- solar radio burst
- solar synchronous satellite
- solar system
- solar system physics
- solar-terrestrial relationship
- solar wind
- solid
- solid angle