| Icing Research Tunnel | Academic & Science |
| Individual Research Training | Academic & Science |
| Innovation Research and Training | Academic & Science |
| Identification, Referral, and Tracking | Academic & Science |
| Item Response Theory | Business |
| Integrated Recycling Technologies | Business |
| Impediment Removal Team | Business |
| Independence Realty Trust | Business |
| Investment Reporting Tool | Business |
| Innovation Round Table | Business |
| IRT Property Company | Business |
| International Recruiting Technology | Business |
| Ice Road Truckers | Community |
| Indiana Repertory Theatre | Community |
| Intensive Residential Treatment | Community |
| Interpersonal Relations Training | Community |
| Infra Red Technology | Computing |
| Integrated Receiver Transcoder | Computing |
| Implementation Review Team | Computing |
| Internet Real Time | Computing |
| Interactive Response Technologies | Computing |
| Immediate Ranging Technology | Computing |
| Integrated Resource Technologies | Computing |
| Interactive Response Technology | Computing |
| Incident Response Technologies | Computing |
| In Regards To | Computing |
| Interactive Restaurant Technology | Computing |
| In Real Time | Computing |
| Infinity Rocket Token | Cryptocurrency |
| Internet Related Technology | Electronics |
| International Road Transport | General |
| Injector Response Time | General |
| Intrepid Rt | General |
| Interboro Rapid Transit | General |
| Infra Red Transmission | General |
| Insanely Retarded Twats | General |
| Intermediate Render Target | General |
| Indian River Towers | General |
| Intermediate Rider Training | General |
| Information Referral Tool | General |
| IRC Remembers This | General |
| Individual Resiliency Training | General |
| Isochronous Real Time | General |
| In Record Time | General |
| Integrity Respect and Trust | General |
| Infrared Radiation Thermography | General |
| Indexed Retention Time | General |
| Infra Red Transmissible | General |
| Internal Remote Translator | General |
| Infinity Radiance Trance | General |
| Interborough Rapid Transi | General |
| Identification Referral Tracking | General |
| Integrated Retail Terminal | General |
| Institute for Recruitment of Teachers | Governmental |
| Innovative Readiness Training | Governmental |
| Immigration Removal Team | Governmental |
| Immigration Review Tribunal | Governmental |
| Interborrough Rapid Transit | Governmental |
| Incident Response Team | Governmental |
| Interborough Rapid Transit | Governmental |
| International Relief Teams | International |
| International Round Table | International |
| In Regard To | Internet |
| I'll Remember That | Internet |
| Internet Related Technologies | Internet |
| ImmunoReactive Trypsin | Medical |
| Independent Review Team | Military and Defence |
| Initial Response Team | Military and Defence |
| International Racquetball Tour | Sports |
| Inertia Racing Technology | Technology |
| Information Resources and Technology | Technology |
| Institute for Responsible Technology | Technology |
| Infared Retaining Technology | Technology |
