GCS
- Australian Football League
- GC (disambiguation)
- Gadsden County School District
- Galactic coordinate system
- Gallantry Cross, Silver
- Game creation system
- Gamma-glutamylcysteine synthetase
- Gaston Christian School
- Gauss Centre for Supercomputing
- Gender-affirming surgery
- General Campaign Star (Canada)
- Geographic coordinate system
- German Church School
- Glasgow Coma Scale
- Glenelg Country School
- Global Civic Sharing
- Global Combat Ship
- Glucocorticosteroids
- Glycine cleavage system
- Gold Coast Suns
- Google Storage
- Gorey Community School
- Government College of Science, Lahore
- Grace Christian School (Florida)
- Grace Church School
- Grand Central Terminal
- Granville County Schools
- Green Cove Springs, Florida
- Greenfield Community School
- Greenville Christian School
- Greenwood College School
- Group Control System
- Group communication system
- Guadalupe Catholic School
- Guildford County School
- UAV ground control station