GPI
- GP1 (disambiguation)
- Gemini Planet Imager
- Gender Parity Index
- General paresis of the insane
- General-purpose input/output
- Generic Product Identifier
- Genuine progress indicator
- George Padmore Institute
- Gibson Plumage Index
- Glacier Park International Airport
- Glass Packaging Institute
- Global Address Space Programming Interface
- Global Partnership Initiative
- Global Peace Index
- Global Poker Index
- Global Press Institute
- Glucose-6-phosphate isomerase
- Glycosylphosphatidylinositol
- Godfrey Phillips India
- Grains per inch
- Granite Peak Installation
- Greenfield Park Primary International School
- Guapi Airport
- Gunung Putri railway station
- Gurley Precision Instruments
- Internal globus pallidus
- SWIFT
- United States national missile defense