OS
Abbreviation with 9 meanings
| Stands for | Operating system |
|---|---|
| Meanings | 9 |
| Categories | Technology & Computing, Transportation & Travel, Medical, Writing & Everyday, Military, Arts & Entertainment, Science & Engineering |
| Also written | O.S., Os |
OS has nine meanings. The most common are Operating system (computer) and Austrian Airlines (airline code); it can also stand for Oculus sinister (left eye), Overall survival, Old Style, Operations Specialist and Ordinary seaman, plus 2 more listed below.
Meanings of OS at a glance
| # | OS stands for | Context |
|---|---|---|
| 1 | Operating system | Technology & Computing › Computer |
| 2 | Austrian Airlines | Transportation & Travel › Airline Code |
| 3 | Oculus sinister (left eye) | Medical › Medication Route |
| 4 | Overall survival | Medical › Hematology and Oncology |
| 5 | Old Style | Writing & Everyday › Citation and Bibliography |
| 6 | Operations Specialist | Military › US Navy and Coast Guard Rating |
| 7 | Ordinary seaman | Transportation & Travel › Maritime |
| 8 | Off-screen | Arts & Entertainment › Film, Television and Theater |
| 9 | Osmium | Science & Engineering › Chemical Element |
1. Operating system
Technology & Computing · Computer Abbreviations
Core software that manages a computer's processor, memory, storage and devices and provides common services to applications. Windows, macOS and Linux dominate desktops and laptops, while Android and iOS run almost all smartphones; embedded devices often use small real-time systems.
Example: The banking app needs at least OS version 16, so older phones can no longer install it.
Pronounced as letters; older documentation sometimes writes O/S. The kernel is the central part of an OS, surrounded by drivers, shells and bundled apps. By number of devices, Android is the most widely installed OS in the world. Apple used the name OS X (read "OS ten") for its Mac system from 2001 until it was renamed macOS in 2016.
2. Austrian Airlines
Transportation & Travel · Airline Code Abbreviations
Vienna-based national airline of Austria, part of the Lufthansa Group and Star Alliance, with a network emphasizing connections to Central and Eastern Europe.
Example: Austrian OS 87 from Vienna to Washington Dulles leaves at 10:20.
ICAO code AUA; callsign "Austrian." Founded in 1957. Lufthansa bought the airline in 2009 after years of losses. Flight attendants wear distinctive red uniforms, including red stockings and shoes.
3. Oculus sinister (left eye)
Medical · Medication Route Abbreviations
Ophthalmic abbreviation for the left eye, seen in eye drop orders, visual acuity records and eyeglass prescriptions. ISMP lists it as error-prone because OS has been confused with AS (left ear) and with "per os" (by mouth).
Example: Prednisolone acetate 1% 1 drop OS QID after cataract surgery.
Latin "oculus sinister"; "sinister" originally meant "left". ISMP recommends writing "left eye" in medication orders. Ophthalmologists record pressures and acuity for OD and OS side by side, and the abbreviations remain standard on optical prescriptions.
4. Overall survival
Medical · Hematology and Oncology Abbreviations
Length of time from randomization or diagnosis until death from any cause, considered the gold-standard end point in cancer clinical trials. It is often reported as a median or as the percentage alive at a fixed time, such as five-year OS.
Example: Five-year OS was 82% in the treatment group, with a hazard ratio for death of 0.71.
OS is objective and clinically meaningful, but it requires large trials with long follow-up and can be blurred by treatments patients receive after the study drug. Regulators sometimes grant accelerated approval based on surrogate end points with confirmatory OS data expected later. On eye prescriptions OS means the left eye (oculus sinister).
5. Old Style (O.S.)
Writing & Everyday · Citation and Bibliography Abbreviations
Marks a date given in the Julian calendar, which was replaced by the Gregorian calendar in different countries at different times. Historians and biographers use it especially for dates in Britain before 1752 and Russia before 1918.
Example: George Washington was born on February 11, 1731 (O.S.), a date now given as February 22, 1732.
Britain and its colonies switched calendars in September 1752, dropping 11 days and moving New Year's Day from March 25 to January 1, which is why Washington's birth year changes too. Biographies often give both forms. Russia adopted the Gregorian calendar in 1918, so the October Revolution of 1917 fell in November by the New Style reckoning.
6. Operations Specialist
Military · US Navy and Coast Guard Rating Abbreviations
Sailors who run the combat information center, operating radar and tactical displays, tracking air and surface contacts, assisting navigation and controlling aircraft and small boats. They feed the picture that commanders use to fight the ship.
Example: OS2 Kim reported a fast-moving surface contact closing from the northeast.
The Coast Guard also uses the OS rating for its command-center and communications watchstanders. Outside the military, OS usually means operating system, and in medicine it can mean oculus sinister (left eye), so watch the context.
7. Ordinary seaman
Transportation & Travel · Maritime Abbreviations
Entry-level deck crew rating on a merchant ship, assisting with watchkeeping, cleaning, maintenance and mooring under the supervision of able seamen.
Example: The new OS spent her first voyage chipping rust and painting the deck.
Ordinary seamen gain sea time to qualify as able seamen. Some fleets also use "deck hand" or "deckhand." In computing, OS means operating system, by far the more common meaning.
8. Off-screen (O.S.)
Arts & Entertainment · Film, Television and Theater Abbreviations
Screenplay notation for dialogue spoken by a character who is physically present in the scene but not visible in the shot, such as someone in the next room. Written in parentheses after the character's name.
Example: SARAH (O.S.): Who left the back door open?
Television scripts often use (O.C.), off-camera, for the same idea. It differs from (V.O.), which is narration or speech not occurring in the scene's space. Standard screenplay format is followed by most US film and TV writers.
9. Osmium (Os)
Science & Engineering · Chemical Element Abbreviations
Osmium (element 76) is the densest naturally occurring element, at about 22.59 grams per cubic centimeter, narrowly ahead of iridium. Hard, brittle osmium alloys were used for fountain-pen nibs, phonograph needles and instrument pivots. Its volatile oxide, osmium tetroxide, stains fats for electron microscopy but is highly toxic.
Example: Post-fix the samples in 1% OsO4 for one hour; Os vapor is toxic, so work in a fume hood.
Smithson Tennant discovered osmium and iridium together in 1803 in the black residue left after dissolving platinum ore in aqua regia. He named osmium from Greek osme (smell) because of the pungent odor of its tetroxide. Which of the two is denser was debated until precise X-ray measurements settled it in favor of osmium.
Related abbreviations
More computer abbreviations
- NTFS – New Technology File System
- OCR – Optical character recognition
- OMR – Optical mark recognition
- OOBE – Out-of-box experience
- OS/2 – Operating System/2
- PC – Personal computer
- PEBKAC – Problem exists between keyboard and chair
- PgDn – Page Down key
See all 92 computer abbreviations →
More airline code abbreviations
- MU – China Eastern Airlines
- NH – All Nippon Airways
- NK – Spirit Airlines
- NZ – Air New Zealand
- OZ – Asiana Airlines
- PR – Philippine Airlines
- QF – Qantas
- QR – Qatar Airways
See all 60 airline code abbreviations →
This entry is for general education and is not medical advice. Abbreviation use varies between institutions; always confirm in context.