OSP
- ChromeOS
- Linux
- Microsoft Windows
- Oblate Sisters of Providence
- Office of Special Plans
- Onafhankelijke Socialistische Partij
- Online service provider
- Open Settlement Protocol
- Open Source Physics
- Open Specification Promise
- Open Syllabus Project
- OpenShot
- Operating System Projects
- Orbital Space Plane
- Orchestra of St Paul's
- Oregon Star Party
- Oregon State Police
- Organic solderability preservative
- Orthosymplectic group
- Osp
- Outer surface proteins
- Outside plant
- Ovince St. Preux