| Abbreviation | Definition |
|---|---|
| IAT | Integration And Test |
| IAU | International Astronomical Union |
| IAV | Inventory Adjustment Voucher |
| IB | InBoard |
| IB | Inert Building |
| IB | Instruction Book |
| IB | Interstellar Band |
| IBDM | International Berthing Docking Mechanism |
| IBE | Inboard Booster Engine |
| IBF | Internally Blown Flap |
| IBFF | Impulse Base Flow Facility |
| IBM | International Business Machines |
| IBSE | Initial Blood Storage Experiment |
| IBSS | Infrared Background Signature Survey |
| IC | Incremental Cost |
| IC | Information Center |
| IC | Initial Condition |
| IC | InterCom |
| IC | Inter-Communications |
| IC | Inter-Computer |