HOS
- Book of Hosea
- Croatian Armed Forces (Independent State of Croatia)
- Croatian Defence Forces
- Croatian Volleyball Federation
- Head of state
- Head of the Schuylkill Regatta
- Hearts of Space
- Heckscher–Ohlin model
- Hellenic Ornithological Society
- Heroes of the Storm
- Higher-order statistics
- Ho (disambiguation)
- Holt–Oram syndrome
- Home Ownership Scheme
- Hornbeck Offshore Services
- Hoss (disambiguation)
- Hostomel Airport
- Hours of service
- Humanistische Omroep
- Saigon Sign Language
- Sikorsky HOS