OS, O.S., Os, O's, or os may refer to:
Osaka (大阪市, Ōsaka-shi) (Japanese pronunciation: [oːsaka]; listen ) is a designated city in the Kansai region of Japan.
Oslo (English pronunciation: /ˈɒzloʊ/, OZ-loh, Norwegian pronunciation: [²uʂlu] ( listen) or, rarer [²uslu] or [ˈuʂlu]) is the capital and the most populous city in Norway.
Oscar Fingal O'Flahertie Wills Wilde (16 October 1854 – 30 November 1900) was an Irish playwright, novelist, essayist, and poet.
Osteoarthritis (OA) is a type of joint disease that results from breakdown of joint cartilage and underlying bone.
The Open Systems Interconnection model (OSI model) is a conceptual model that characterizes and standardizes the communication functions of a telecommunication or computing system without regard to their underlying internal structure and technology.
An oscilloscope, previously called an oscillograph, and informally known as a scope, CRO (for cathode-ray oscilloscope), or DSO (for the more modern digital storage oscilloscope), is a type of electronic test instrument that allows observation of constantly varying signal voltages, usually as a two-dimensional plot of one or more signals as a function of time.
Oscar De La Hoya (/deɪləˈhɔɪ.ə/; born February 4, 1973) is a former professional boxer who competed from 1992 to 2008. He holds dual American and Mexican citizenship.
Osteoporosis is a disease where increased bone weakness increases the risk of a broken bone. It is the most common reason for a broken bone among the elderly.