| Abbreviation | Definition |
|---|---|
| I/FU | InterFace Unit |
| I/O | Input/Output |
| I/OB | Input/Output Bus |
| I/OC | Input/Output Controller |
| I/OMI | Integration/Operations and Maintenance Instruction |
| I/OP | Input/Outboard Profile |
| I/OT | Input/Output Test |
| I/OU | Input/Output Unit |
| I/P | In Progress |
| I/T | InterTank |
| I/V | Inlet Valve |
| IA | Implementation Agency |
| IA | Input Axis |
| IA | Inverter Assembly |
| IA | Issuing Agency |
| IA/V | Internal Audio and Video |
| IAA | International Aerospace Abstracts |
| IAB | IUS (Inertial Upper Stage) Assembly Building |
| IAC | Instituto de Astrofisica de Canarias, Spain |
| IAC | Integrated Analysis Capability |