STAC
- C1 domain
- Compagnie générale française des transports et entreprises
- Crime hotspots
- Geographic data and information
- Graphic Adventure Creator
- Lempel–Ziv–Stac
- List of airline codes (S)
- Open standard
- STACS
- Saint Thomas Aquinas College (Sogod)
- Sepak Takraw Association of Canada
- Service de transport adapté de la Capitale
- SigmaTel
- Sirtuin-activating compound
- Southern Theatre Arts Centre
- Special Transit Advisory Commission
- St Andrew's College, Christchurch
- St. Thomas Aquinas College
- Stac Electronics
- Supersonic Transport Aircraft Committee
- Supervisor Mode Access Prevention