OS, O.S., Os, O's, or os may refer to: Computing. Operating system, computer system software that manages the hardware and software of a computer. Open source (disambiguation) OpenStack, a software platform for cloud computing. Medicine. os, a bone in french. os or ostium, a mouth or mouth-like opening. external os, the external orifice of the uterus. internal os, the internal orifice of the uterus. per os, meaning "ingestion by mouth" os or ostium, the opening of a coronary artery. O.S.
https://en.wikipedia.org/wiki/OS