Provider Sponsored Organizations. Organizations ofphysicians, group practices, hospitals that can create a health planproduct such as an HMO, PPO etc.

Personal Services Operating System, an administrative data base used to maintain and update employee information.

According to some industry insiders, pSOS stands for plug-in Silicon Operating System but the official stance is that it is not an abbreviation, just a made-up word. (The original authors will not divulge the origin of the term.)