IOS (disambiguation)
- BIOS (disambiguation)
- Cisco IOS
- Cisco IOS XE
- Cisco IOS XR
- I/O System (86-DOS)
- I/O System (MS-DOS)
- I/O System (disambiguation)
- IOS (Wii firmware)
- IOS Press
- Ilhéus Jorge Amado Airport
- Illinois Ornithological Society
- Independent on Sunday
- Input/Output Control System
- Input/Output Supervisor
- Institute of Oriental Studies of the Russian Academy of Sciences
- Instructor operating station
- International Open Series
- International Organization for Standardization
- International Organizations for Succulent Plant Research
- International operator services
- Internet operating system
- Interorbital Systems
- Interorganizational system
- Investors Overseas Service
- Io (disambiguation)
- Ios
- Ireland on Sunday
- Sodor (fictional island)
- The Atlas Society
- XIOS