| Inter-Residence Council | Academic & Science |
| I Repeat Classes | Academic & Science |
| Item Related Check | Accounts and Finance |
| International Reply Coupon | Accounts and Finance |
| Circle (ak) | Airport Code |
| Innovation Relay Centres | Business |
| International Resistive Company, Inc. | Business |
| Individual Returnable Coupon | Business |
| Individual Rest | Business |
| Intermin Resources Ltd | Business |
| Independent Restaurant Coalition | Business |
| Innovation Relay Centre | Business |
| Inspection Release Certificate | Certifications |
| Indignant Revolutionary Channel | Community |
| International Relations Center | Community |
| International Rescue Committee | Community |
| Innovative Recreation Cooperative | Community |
| Innova Riders Club | Community |
| Independent Review Committee | Community |
| Information Resource Center | Community |
| I Repeat Class | Community |
| International Rostrum of Composers | Community |
| Institutional Review Committee | Community |
| Internet Ready Computer | Computer Hardware |
| Infra Red Camera | Computing |
| Interrupt Request Controller | Computing |
| Internet Related Communication | Computing |
| Inter Region Communication | Computing |
| Innovation Relay Center | Computing |
| Incident Response Capability | Computing |
| Incident Response Committee | Computing |
| Incident Response Coordinator | Computing |
| Intel Reseller Center | Computing |
| Internet Resource Center | Computing |
| Ircam Sound Format | File Type |
| International Rally Challenge | General |
| Intercontinental Rally Challenge | General |
| Integrated Radio Chassis | General |
| International Racing Consultants | General |
| Independent Race Classes | General |
| International Racing Circuit | General |
| Integrated Roll Cage | General |
| Istanbul Racing Circuit | General |
| Indian Roads Congress | General |
| International Road Congress | General |
| Internal Recirculation | General |
| Intelligent Ride Control | General |
| Israeli Roadster Club | General |
| Inter Regional Corridor | General |
| Issoire Retromobile Club | General |
| Irritating Repetive Chite | General |
| Ironically Retarded Comment | General |
| International Return Coupon | General |
| Independent Redistricting Commission | General |
| Industrial Refrigeration Consortium | General |
| Instructional Resource Center | General |
| Interactive Resource Center | General |
| Irrational Rhubarb Chompers | General |
| International Relay Channel | General |
| Intgrated Communication Resource | General |
| Illinois Resource Center | General |
| Incrementally Related Carriers | General |
| Intl Rescue Comm | General |
| Interhemispheric Resource Center | General |
| Intelligent Release Control | General |
| Islamic Research Center (Pakistan) | General |
| Irish Republican Constabulary | Governmental |
| Inland Revenue Commissioner | Governmental |
| Impact Resistance lens Certification | Governmental |
| Irish Research Council | Governmental |
| Insurance Research Council | Governmental |
| Internal Revenue Code | Governmental |
| Institute for Research in Construction (Part of NRC, Canada) | Governmental |
| Internet Relay Chat | Information Technology |
| International Residential College | International |
| International Rewards Centre | International |
| International Relations Committee | International |
| International Radiation Commission | International |
| International Reply Coupons | International |
| International Rating Certificate | International |
| Internet Rely Chat | Internet |
| Internet Resource Channel | Internet |
| Incrementally Related Carrier | Medical |
| Initial Response Cell | Military and Defence |
| International Red Cross | Military and Defence |
| International Residential Code | Real Estate |
| Indian River County | Regional |
| Inland Regional Center | Regional |
| Circle, Alaska USA | Regional |
| Internet Ready Commands | Softwares |
| Internet Ralley Competition | Sports |
| Internet Running Club | Sports |
| International Record Carrier | Telecommunication |