| I&C | Information and Communication  
| Technology |
| I&C | Installation and Checkout
| Technology |
| I&C | Issues and Criteria
| Others |
| I&D | Incision & Drainage
| Medical |
| I&E | Income & Expenditure
| Others |
| I&E | Income and Expenditure
| Finance |
| I&E | Integration and Evaluation
| Others |
| I&M | Inspection and Maintenance
| Others |
| I&M | Installation and Maintenance
| Others |
| I&M | Instrumentation and Measurement
| Science |
| I&M | Instrumentation and Measurement Magazine
| Publication |
| I&MT | Information and Media Technologies
| Technology |
| I&N | Infiniti and Nissan
| Company, Transport |
| I&O | In and Out
| Others |
| I&O | Infrastructure & Operations
| Others, Technology |
| I&O | Inlet And Outlet
| Hardware |
| I&O | input and output (fluid monitoring)
| Medical |
| I&O | input and output (fluid)
| Others |
| I&P | Imaging and Printing
| Technology |
| I&PR | Information & Public Relations
| Agency, Communication |
| I&PS | Institutional And Program Support
| Finance |
| I&R | Interchangeability And Replaceability
| Others |
| I&R | Interchangeable (Interchangeability) & Replaceable (Replaceability)
| Others |
| I&R | Interchangeable and Replaceable
| Others |
| I&RS | Instrument And Range Safety
| Military |
| I&RTS | Integration & Run Time Specification
| Technology |
| I&S | Interchangeability And Substitutability
| Others |
| I&T | Integration And Test
| Technology |
| I&TRR | Integration And Test Readiness Review
| Technology |
| I&VT | Instrumentation and Vehicle Testing
| Technology, Transport |
| I&W | Indications and Warning
| Military |
| I&W | Indications and Warnings
| Others |
| I'd | I Should
| Communication, Language |
| I'd | I would
| Communication, Language |
| I'll | I Will
| Communication, Language |
| I'M | I Am
| Communication, Language |
| I'M | I am (English language)
| Others |
| I'VE | I Have
| Communication, Language |
| I-131 | Radioactive Iodine
| Element, Isotope |
| I-CARE | IBM Collaborative Academia Research Exchange
| Technology |
| I-CAS | Isuzu Clean Air Solutions
| Company |
| I-DAY | Day Intelligence Indicators Are Recognized
| Others |
| I-DEA | Idaho Distance Education Academy
| Education, Academy |
| i-DL | internal Data Language
| Computer Programming |
| I-GOOS | IOC-WMO-UNEP Committee for the Global Ocean Observing System
| Organization |
| I-GPRF | Isothermal General Purpose Rocket Furnace
| Technology, Transport |
| I-LOS | Initial data Load-Out Set
| Others |
| I-PAL | Improved Phase Alternate Line
| Technology |
| I-PORT | Individual Soldier's Portal (Into the Synthetic Battlefield)
| Military |
| I-PWG | Industry Pharmacogenomics Working Group
| Organization |