- ionosphere
- ion propulsion
- ion rocket
- ions
- -ions
- ion trap
- IOOF
- iota
- iotacism
- iotacisms
- iotas
- IOU
- IOUs
- -ious
- Iowa
- Iowa Central Community College
- Iowa City
- Iowa Lakes Community College-Estherville
- Iowa Lakes Community College-South
- Iowa River
- Iowas
- Iowa State University
- Iowa Wesleyan College
- Iowa Western Community College
- Iowa Western Community College-Clarinda