Office of Strategic Services
Open Source Software
Operational Support Systems
Object Service Standard (SEMI)
Objective Supply System
Observatory of the Sahara and the Sahel
Occupant Sensing System
Ocean Surveillance System
Off Screen (cinematography)
Office for Special Support (academic support for students with special needs)
Office of Space Science
Office of Space Station (NASA)
Office of Space Systems
Office of Special Services
Office of Statistical Standards
Office of Student Services
Office of Systems Support
Office of the Secretary of State
Office Support System
Ofte Stillede Spørgsmål (Danish: Frequently Asked Questions)
Ogrenci Secme Sinavi (Turkish university exam)
Oh Shoot Situation (polite form)
Oifig Schrúdóir na Scannán (Film Censor's Office, Ireland)
Old School Soldiers
Old Soft Shoe
On Site Service(s)
On-Board Support Software
OnDO SIP Server
One Stop Shopping
Online Schedule System
Online Search Service
Open Simulation System
Open Sky System (Audi)
Open Sound System (Unix digital audio architecture)
Open System Solution
Operation Support System
Operational Services Switch
Operational Storage Site
Operational Support Services
Operational Support Summary
Operational Support System
Operational Support System (THREAT)
Operations Support Services
Operations Support Squadron
Operations Support System(s)
Operator Seat Switch
Operator Service System
Optical Sight System
Optical Storage System
Optical Surveillance System
Optics Support Structure
Optimizing SubSystem
Optional State Supplementation
Ordinary Strength Steel
Organizational Supply Support
Ormeau State School (Gold Coast, Australia)
Ossetic (linguistics)
Out of School Suspension
Output Sub System
Outside Storage
Outside Surface
Over Speed Sensor (railroad industry)
Over-The-Shoulder Shot (video photograpy)
Overall System Sensitivity (radar)
Oxenford State School (Gold Coast, Australia)
