| Acronym | Definition |
|---|
| GCSI | Gastroparesis Cardinal Symptom Index |
| GCSI | Grupo Colombiano de Seguridad Integral (Spanish: Integral Colombian Safety Group) |
| GCSI | Graduate Certificate in Social Impact (Australia) |
| GCSI | Global Change Strategies International (Ottawa, Ontario, Canada) |
| GCSI | Governmental Consultant Services Inc (Lansing, MI) |
| GCSI | Grand Commander of the Star of India (knight) |
| GCSI | Global Community Security Institute (Michigan State University) |
| GCSI | Genetic Computer Strand Implants (Earthsiege terminology game) |
| GCSI | Ginésy Christine Secrétariat Indépendant |