TOS
- Atari TOS
- DOS/360 and successors
- Gy's sampling theory
- TOC (disambiguation)
- TOS-1
- Tam o' Shanter (cap)
- Television Oita System
- Temple of Set
- Temple of Shadows
- Tennessee Ornithological Society
- Terminal Operating System
- Terms of service
- Testament of Solomon
- The Oceanography Society
- Theosophical Order of Service
- Thoracic outlet syndrome
- ToS2 (disambiguation)
- Toos (disambiguation)
- Toss (disambiguation)
- Tosyl
- Town of Salem
- Toxic oil syndrome
- Tree of Savior
- Tromsø Airport
- Trucial Oman Scouts
- Type of service
- T·O·S (Terminate on Sight)