| GMT | Galaxy Mean Time 
| Others |
| GMT | Gambia Maybe Time
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| GMT | General Motor Transport
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| GMT | General Motors Truck
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| GMT | General Motors Trucks
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| GMT | General Multi-Tasker
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| GMT | Generative Modeling Technologies
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| GMT | Generic Mapping Tool
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| GMT | Generic Mapping Tools
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| GMT | Get Me Tight
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| GMT | Get Moving Today
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| GMT | Ghana Maybe Time
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| GMT | Giant Magellan Telescope
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| GMT | Gigabyte Management Tools
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| GMT | Glass Mat Thermoplastic
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| GMT | Glass Mat Thermoplastics
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| GMT | Global Marine Travel
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| GMT | Global Membership Team
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| GMT | Gonzalez Model Talent
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| GMT | Good Mother Tincture
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| GMT | Goodbye Mankind Time
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| GMT | Goodman Martinez Thompson
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| GMT | Gospel Music Television
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| GMT | Great Magazine of Timepieces
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| GMT | Greek Maybe Time
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| GMT | Green Mobility Trophy
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| GMT | Green Mountain Transit
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| GMT | Greenwhich Mean Time
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| GMT | Greenwich Mean Time
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| GMT | Greenwich Mean Time (now obsolete)
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| GMT | Greenwich Meridian Time
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| GMT | Greenwich Moaning Time
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| GMT | Grinding My Teeth
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| GMT | Ground Maintenance Technics
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| GMT | Ground Moving Target
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| GMT | Grounds Maintenance Tractor
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| GMT | Groves Manufacturing & Tooling
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| GMT | Guided Missile Transporter
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| GMT | Guilde Mondiale des Tractionnistes
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| GMT | Gummi Metall Technik
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| GMT | Gums, Mouth, Tonsils
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| GMT | Guyot Motorcycle Team
| Others |