OS

OS may refer to:

• O.S. Old Stonyhurst, an old boy of the ancient Jesuit public school, Stonyhurst College
• O.S. Engines, a Japanese manufacturer of model aircraft engines
• Ocean Science, an Oceanographic Journal published by the European Geosciences Union.
• Oculus sinister, meaning "left eye" in eyeglass prescriptions
• "Old Style date" (as "O.S."), a date designation indicating derivation from the Julian Calendar, as opposed to "N.S." indicating derivation from the Gregorian Calendar (see Old Style and New Style dates)
• Open SEAT, a tennis tournament in Barcelona now known as the Torneo Godó
• Open source, a software development model
• Operating system, a software that manages the hardware and software of a computer
• Ordinary Seaman (occupation), an unlicensed member of the deck department of a merchant ship
• Ordnance Survey, the national mapping agency for Great Britain
• Ohtahara syndrome, a brain disorder
• Opening snap, a heart sound present in individuals with AV valve stenosis
• Outlaw Star, a manga and anime series
• Austrian Airlines (IATA designator)
• Ossetic language (ISO 639-1 abbreviation)
• Ordnance Sergeant
• Overall Survival

os may refer to:

• os, a mouth or external opening (from the Latin), also ostium. In particular:
  • external os, the external orifice of the uterus
  • internal os, the internal orifice of the uterus
  • os or ostium, the "mouth" of a coronary artery

Os may refer to:

• Os, Hedmark, a municipality in Norway
• Os, Hordaland, a municipality in Norway
• Os, Østfold, a parish in Norway
• Ōs, in Old English denoting a god in Anglo-Saxon paganism
• Osmium, a chemical element whose symbol is "Os"
• Os du Randt (born 1972), South African rugby player
• Os Guinness (born 1941), English author and social critic
• Oś, Kluczbork County, Poland
• Osiedle, a name for a housing estate in Poland
• "Os", an episode of the television show Fringe

O's may refer to:

• Baltimore Orioles
• Leyton Orient

See also

• Per os, a medical term for ingestion by mouth
• Object sexuality, sexual attraction to inanimate objects
• Oral sex, sexual activity involving the stimulation of the genitalia of a sex partner by the use of the mouth, tongue, teeth or throat.
• OutSystems, multinational software company which operates in the agile software development market.

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