| I-REFCU | Ingersoll-Rand Employees Federal Credit Union  
| Company |
| I-UAL | Internal Ultrasonic Assisted Liposuction
| Medical |
| I-VMS | Integrated Value-Added Management System
| Technology |
| I-VTEC | Intelligent Variable-Valve Timing Electronic Control
| Technology |
| I-YEL | Inspiring Young Emerging Leaders
| Education |
| i. e. S. | im engeren Sinne
| Communication, Language |
| i. w. S. | im weiteren Sinne
| Communication, Language |
| I.B.C. | Inside Back Cover
| Marketing, Publication |
| i.e. | Id Est (Latin: For Example)
| Others |
| i.e. | Id Est (that is)
| Others |
| i.e. | Id Est. (Latin: that is)
| Communication, Language |
| i.e. | that is ("id est" [Lat.])
| Others |
| i.e. | that is (id est [Lat.])
| Others |
| I.F.C. | Inside Front Cover
| Marketing, Publication |
| i.LINK | IEEE 1394, High Performance Serial Bus, implementation
| Technology |
| i.m. | intramuscular
| Medical |
| I.N | Independent Nation
| Country |
| I.N.T.O | Irish National Teacher's Organisation
| Organization |
| I/A | Interface Adapter
| Hardware, Technology |
| I/A | Internal Access
| Computer Programming |
| I/B | Inboard
| Military |
| I/B | Instructed By
| Education |
| I/C | In Charge
| Others |
| I/C | Intercept
| Military |
| I/C | InterCom
| Communication, Technology |
| I/C | Intercostal
| Biology |
| I/D | Intradermal
| Medical |
| I/E | Input Electronics
| Electronics |
| I/F | Interface
| Others |
| I/F/O | In Front Of
| Others |
| I/FU | InterFace Unit
| Hardware, Technology |
| I/I | Infiltration and Inflow
| Others |
| I/O | In-Port Operations
| Transport |
| I/O | Input/ Output
| Others |
| I/O | Input/Output
| Technology |
| I/O | Interest Only
| Finance |
| I/O | Intraosseous
| Medical |
| I/OB | Input/Output Bus
| Technology, Computing |
| I/OC | Input/Output Controller
| Technology, Computing |
| I/OMI | Integration/Operations and Maintenance Instruction
| Technology |
| I/OP | Input/Outboard Profile
| Technology, Transport |
| I/OP | Input/Output Processor
| Technology, Computing |
| I/OT | Input/Output Test
| Technology |
| I/OU | Input/Output Unit
| Technology |
| I/P | In Progress
| Others |
| I/P | Intraperitoneal
| Medical |
| I/R | Interchange/Replacement
| Others |
| I/R | Internment/resettlement
| Others |
| I/R | Internment/Resettlement (Battalion)
| Military |
| I/T | InterTank
| Hardware |