out of service
Object Oriented System
On-Orbit Station
Orbit-to-Orbit Shuttle
Orbit-to-Orbit Stage
Object-Oriented Systems
Ocean Observing System
O,O,S-trimethyl phosphorothioate
Object Oriented Systems
Occupational Overuse Syndrome
Ocean Observing Systems
Office of Operational Safety
Office of Operational Systems
Off-line Operating Simulator
Ohio Ophthalmological Society
Only One Shot
On-Orbit Summary
Open Ocean Surveillance
Operational Operating System
Operational Override Switch
Opportunities of Selection
optical-oscillator strength
orbicularis oris superior
Ore/Oil Ship
OTM Overhead Signal
Out Of Sight
Out Of Stock
Out of Synch
Out Of Synchronization
Out-Of-Sequence