| Abbreviation | Definition |
|---|---|
| HZ | Hrvatska Zeljeznica |
| HZMB | Hong KongZhuhaiMacau Bridge |
| HZMB | Hong Kong–Zhuhai–Macau Bridge |
| I | Intersection |
| I/O | In-Port Operations |
| I88 | Interstate Highway 88 (Illinois and New York) |
| I99 | Alexandria Airport |
| IA | Indian Airlines |
| IA | Inspector Aircraft |
| IAC | Idle Air Control |
| IACP | International Association of Chiefs of Police |
| IAD | Washington Dulles International Airport |
| IAF | Initial Approach Fix |
| IAH | Houston Intercontinental Airport |
| IAM | Institute of Advanced Motorists |
| IAOB | International Automotive Oversight Bureau |
| IAP | Instrument Approach Procedure |
| IAP | Internatioal Air Port |
| IAP | International Airline Professional |
| IAPA | Instrument Approach Procedures Automation |