What does OS stand for?

Austrian Airlines - ICAO designator (AD)

By Mouth - Pharmacy (DAVI)

Obese Strain - White leghorn

Object-Subject - Education of the hearing-impaired

Oblique Sounding - Telecommunications (OA)

Observation-Scouting Plane - When first two letters in Navy designation

Observation Squadron (SAUS)

Observation Station (SAUS)

Observer School (SAUS)

Observing Station - Marine science (MSC)

Occipitosacral - Medicine (EDAA)

Occupational Safety (DAVI)

Oceanic Society (EA)

Oceanography Section (SAUS)

Oceans - Federal Information Processing Standard (FIPS) country code (GEON)

Ocean Station - Maps and charts

Ocean Surveillance (ACAE)

Octane Switch - Automotive engineering

Octavian Society (EA)

Oculus Sinister - Left Eye - Ophthalmology

Odd Symmetric

Offensive Support (SAUS)

Office of Supply (SAUS)

Office of Systems - NASA (KSC)

Office of the Secretary

Officer of the Sword - Civil War term

Officers' Steward - Ranking title - British Women's Royal Naval Service

Office Surgery (SAUS)

Office System

Official Scorer - Baseball term (NDBD)

Official Station

Off Scale (IAA)

Off Screen - or Stage

Offset

Off Stage (SAUS)

Oglala Sioux - NCIC Indian nation code (NCIC)

Ohio State (SAUS)

Ohio State Reports - A publication (DLA)

Oil Sand (SAUS)

Oil Shale (SAUS)

Oil Solenoid

Oil Solubility (SAUS)

Oil-Soluble (SAUS)

Oil Solvent (SAUS)

Oil Switch

Old Saxon - Language, etc.

Old School

Old Series

Old Side

Old Standard - Currency (ROG)

Old Style - Printing (NTCM)

Old Style - Calendar, previous to 1752

Old Style date (SAUS)

Omega Society - Defunct (EA)

Omenn Syndrome - Medicine (EDAA)

Omnibus Society - British

One Shot

One Side

One-Stop - Aviation

Only Son

On-Orbit Station - NASA (MCD)

On Sale

On Sample

On Schedule

On Sheet (WGA)

On Side

On-Site

On Spot (ROG)

On Station - Military

On Switch

Opening Snaps - Cardiology

Open Shop (SAUS)

Open Side (SAUS)

Open Statement (SAUS)

Open Subroutine (SAUS)

Open System (SAUS)

Operating Schedule - Field stations (MCD)

Operating Software (MCD)

Operating Strength - Military technology (DDF)

Operating System - Computer science (BUR)

Operational Sequence (KSC)

Operational Sheets

Operational Software (SAUS)

Operational Specialist - Navy

Operational Suitability

Operational Supplements - Air Force (MCD)

Operation Sandstone - Atomic weapons testing

Operation Sheet (SAUS)

Operation Smile (EA)

Operation Snapper - Atomic weapons testing

Operations Specialist - Navy (DNAB)

Operations Superintendent (SAUS)

Operations Support - Office of U.S. Foreign Disaster Assistance

Operations System (SAUS)

Operation Suburbia - Defunct (EA)

Operator Service (SAUS)

Operator's Set

Oppose - Telegraphy (PCTE)

Optical Scanner (SAUS)

Optical Scanning - Computer science

Optical Society (NADA)

Optical Spectroscopy (SAUS)

Optical System (SAUS)

Optics Subsystem

Optimum Size (ELAL)

Option Spreading - Investment term

Oral Surgery

Oral Suspension - Pharmacy

Orbital Servicing (SAUS)

Orbiter CEI - Contract End Item Specification - NASA (NASA)

Orderly Sergeant (SAUS)

Order of Servites

Order Sheet

Ordinary Seaman - British

Ordnance School - Army (MCD)

Ordnance Server (SAUS)

Ordnance Services - Military - British

Ordnance Specifications - Navy

Ordnance Survey

Oregon State (SAUS)

Oregon Steel Mills - NYSE symbol (SPSG)

Organic Solvent (SAUS)

Organic Synthesis (SAUS)

Organizational Source - Online database field identifier - Computer science

Organizational Support (SAUS)

Organizations System (IAA)

Organization System (SAUS)

Organosilicon (SAUS)

Original Series

Ornamental Stitching (DNAB)

Oro Sellado - Standard Gold - Business term - Spanish

Orthogonal System (SAUS)

Orthopedics (DAVI)

Orthopedic Surgery (DAVI)

Orton Society - Later, ODS (EA)

Osgood-Schlatter's Disease - Medicine

Osiriscript

Osmotic Shock

Osnabrueck - German license plate city code

Osteogenic Sarcoma - Medicine

Osteosarcoma - Oncology

Osteosclerosis - Medicine (DAVI)

Oszillator im Sender (SAUS)

Other Side - A publication (BRI)

Other Sources

Otherwise Specified (MSA)

Outer Segment

Outer Sheath - Botany

Outer Space (SAUS)

Outlaw Shark - RADAR surveillance - Naval Electronic Systems Command

Outline Square Condition - Vision

Out of Stock (NTCM)

Output Secondary - Electronics

Output Signal (SAUS)

Output Source (SAUS)

Output Specification (SAUS)

Output Spy

Output Store (SAUS)

Output System (SAUS)

Out Secondary (SAUS)

Outside

Outside Sales (TRID)

Outside Sentinel

Outsize - Of clothes

Outstate (SAUS)

Outstation (MCD)

Out Stealing - Baseball

Overall Size (SAUS)

Overall Survival - Medicine

Overlong Sentence - Used in correcting manuscripts, etc.

Overscene - Films, television, etc.

Oversea - Military

Overseas Service (SAUS)

Overshoot (SAUS)

Oversize (AAG)

Overspecificity - Psychometrics

Overstressing (SAUS)

Over-the-Horizon Targeting System (MCD)

Over-the-Shoulder Cinematography (NTCM)

Over the State - Regarding distribution

Own Ship - Navy (CAAL)

Oxygen Saturation (DB)

Oxygen Sensor - Automotive engineering

Oxygen Service (DNAB)

Sarnia Public Library, Ontario - Library symbol - National Library of Canada (NLC)

Shell Development Co. - Research code symbol

Test Oscilloscope - JETDS nomenclature - Military (CET)

Warder Public Library of Springfield and Clark County, Springfield, OH - Library symbol - Library of Congress (LCLS)

Oberseminar (SAUS)

Oscan - Linguistics (IEL)

Osmium - Chemical element

Left Eye - Therapy term (CTAA)

Mouth - Medicine (BCRP)

Ocean Station (ODA)

Old Series - Linguistics (IEL)

Only Son (WDAA)

On-Orbit Station - NASA (NAKS)

Opera Seria - Music (GROV)

Outstanding (ELAL)