STO
- Caprica
- Council of Labor and Defense
- Emoticon
- NATO Science and Technology Organization
- Professional wrestling throws
- STO (professional wrestling)
- STO-nG basis sets
- STOS (disambiguation)
- Safe Torque Off
- Security through obscurity
- Security token offering
- Semi-automatic train operation
- Sergio Tofano
- Service du travail obligatoire
- Slater-type orbital
- Société de transport de l'Outaouais
- Sojourner Truth Organization
- South Tottenham railway station
- SportsTime Ohio
- Star Trek Online
- State Trading Organization
- Statoil
- Stockholm
- Stoney language
- Stø
- United States Air Force Special Tactics Officer