73 OAS definitions

Organization of American States 
Offensive Air Support 
Office of Applied Studies 
Offensive Avionics System 
Old Age Security 
Obstacle assessment surface 
Office Automation System 
Office of Aircraft Services 
One-to-All Scatter 
Option Adjusted Spread 
Orbiter Aeroflight Simulator 
Orbiter Atmospheric Simulator 
Orbiter Avionics System 
Office of Administrative Services 
Open Application Server 
Organisation of American States 
Obstacle Assessment Surfaces 
Office of the Assistant Secretary 
Online Assessment System 
Operational Areas 
Operations Applications 
optical alignment sights 
Oracle Application Server 
Oral allergy syndrome 
Orbit Analysis System 
Orbital Analysis System 
Orbiter Attachment System 
Orbiter Avionics Simulator 
O-acetyl-L-serine 
O-acetylserine