| Acronym | Meaning |
| HUN | Hungarian Language (ISO 639-2 Code) |
| HUN | Hungary (ISO 3166 Trigram) |
| HURD | Hird Of Unix-Replacing Daemons (cf. Hird) |
| HV | Upper Volta (ISO 3166 Digram; Obsolete 1984) |
| HVAP | High Velocity Armour Piercing (ammunition) |
| HVM | High Velocity Missile |
| HVO | Upper Volta (ISO 3166 Trigram; Obsolete 1984) |
| HVP | HarborView Properties - High Vacuum Process - Hydrolized Vegetable Protein |
| HVU | High Value Unit (military) |
| HW | Hardware -High Water (nautical Charts) |
| HY | Armenian Language (ISO 639-1 Code) |
| HYE | Armenian Language (ISO 639-2 Code) |
| HZ | Haze (METAR Code) |
| HZ | Herero Language (ISO 639-1 Code) |
| HZ | Hertz |
| I | Iodine - One (in Roman Numerals) |
| I.E. | Id Est (Latin |
| I/ITSEC | Interservice/Industry Training |
| I2WD OR I?WD | U.S. Intelligence And Information Warfare Directorate (CERDEC) |
| IA | Interlingua Language (ISO 639-1 Code) |
| IA | Iowa (postal Symbol) |
| IAAF | International Association Of Athletics Federations (International Amateur Athletics Federation From 1912-2001) |
| IAAL | I Am A Lawyer |
| IAB | International Association For Biologicals |
| IACREOT | International Association Of Clerks |
| IAD | Ion Assisted Deposition |
| IADS | Integrated Air Defence System |
| IAEA | International Atomic Energy Agency |
| IAF | Industrial Areas Foundation |
| IAFG | Information Assurance Focus Group |
| IAI | International African Institute - Israel Aircraft Industries |
| IANA | Internet Assigned Numbers Authority |
| IANAL | I Am Not A Lawyer |
| IAQ | Indoor Air Quality - Infrequently Asked Questions |
| IAS | Image Assessment System |
| IATA | International Air Transport Association |
| IAU | International Association Of Universities - International Astronomical Union |
| IAUC | International Astronomical Union Circular |
| IAW | In Accordance With |
| IB | International Baccalaureate |
| IBA | Important Bird Area |
| IBDM | Information Based Decision Making |
| IBDS | Integrated Biological Detection System - International Business Development Specialist |
| IBM | International Business Machines |
| IBO | Igbo Language (ISO 639-2 Code) |
| IBRD | International Bank For Reconstruction And Development (part Of The World Bank) |
| IBS | Irritable Bowel Syndrome |
| IC | Ice Crystals (METAR Code) - Iceland (FIPS 10-4 Country Code) -Integrated Circuit |
| ICANN | Internet Corporation For Assigned Names And Numbers |
| ICAO | International Civil Aviation Organization |