| GTTC | Genetic Toxicology Technical Committee 
| Others |
| GTTC | Genetics Translational Technology Core
| Others |
| GTTC | Geoscience Technology Training Center
| Others |
| GTTC | Global Tax Treaty Commentaries
| Others |
| GTTC | Global Technology and Training Center
| Others |
| GTTC | Global Trade Technology Center
| Others |
| GTTC | Global Travel Training Community
| Others |
| GTTC | Goodfellow Technical Training Center
| Others |
| GTTC | Gordon Tilden Thomas Cordell
| Others |
| GTTC | Government Technology and Telecommunications Committee
| Others |
| GTTC | Government Toolroom and Training Center
| Others |
| GTTC | Greater Toronto Transportation Conference
| Others |
| GTTC | Ground Testing Technical Committee
| Others |
| GTTC | Gt and Touring Car Championship
| Others |
| GTTC | Gymnastics Tape Trading Club
| Others |