| Independent Researchers Group | Academic & Science |
| Intelligent Robotics Group | Academic & Science |
| Internet Research Group | Academic & Science |
| Institutional Research Grant | Academic & Science |
| Implementation Research Group | Academic & Science |
| Ideographic Research Group | Academic & Science |
| Interest Rate Guarantee | Accounts and Finance |
| Lockhart River | Airport Code |
| Independent Reassessment Group | Business |
| Indep. Res. | Business |
| Imvescor Restaurant Group Incorporated | Business |
| Ignite Restaurant Group | Business |
| Industrial Realty Group, LLC | Business |
| IRGIgnite Restaurant Group | Business |
| Insurance Recovery Group | Business |
| Islamic Resource Groups | Community |
| Islamic Resource Group | Community |
| Internet Resource Guide | Computing |
| Internet Resource Group | Computing |
| Intensive Rotational Grazing | General |
| Individual Registered Girl | General |
| Intergovernmental Reference Guide | General |
| itial Review Group | General |
| Independent Regulators Group | General |
| Integrated Resources Group | General |
| Inter Record Gap | General |
| International Realty Group | General |
| Industry Retail Group | General |
| Immediate Release Granules | General |
| International Risk Group | General |
| Industrial Realty Group | General |
| International Resources Group | General |
| Interior Resource Group | General |
| Implementation Review Group | General |
| Integrated Review Groups | General |
| Individual Route Guidance | General |
| Imperial Racing Green | General |
| Infiniti Retail Group | General |
| Immunity Related GTPases | General |
| Information Resource Group | General |
| Instantaneous Rate of Green | General |
| Inner Rim Grinding | General |
| Ice River Genetics | General |
| Internationally Recognised Government | Governmental |
| Institute for Reforming Government | Governmental |
| International Repeater Group | International |
| International Resource Group | International |
| International Recycling Group | International |
| Integrity Rehab Group | Medical |
| Iraq Republic Guard | Military and Defence |
| Lockhart Rivers, Queensland, Australia | Regional |
| Inertial Rate Gyroscope | Space Science |
| Inner Roll Gimbal | Space Science |
