| AR&O | Airline Repair & Overall 
| Others |
| AR&O | Airplane Requirements & Objectives
| Others |
| ARO | Abrasion Resistant Overlay
| Others |
| ARO | Academic Recruitment Organization
| Others |
| ARO | Academic Research Online
| Others |
| ARO | Academic Research Organization
| Others |
| ARO | Accelerated Research Opportunities
| Others |
| ARO | Acceleration for Rollover
| Others |
| ARO | Accessibility Resources Office
| Others |
| ARO | Accessibility Results and Objectivity
| Others |
| ARO | Accident Records Office
| Others |
| ARO | Accounts Receivable Operations
| Others |
| ARO | AccuGrade Ready Option
| Others |
| ARO | Action Racing Online
| Others |
| ARO | Adaptive Recreation Opportunities
| Others |
| ARO | Adirondack River Outfitters
| Others |
| ARO | Admissions and Records Office
| Others |
| ARO | Aerosol Solid
| Others |
| ARO | Affordable Requirements Ordinance
| Others |
| ARO | After Receipt of Order
| Others |
| ARO | After Run Oil
| Others |
| ARO | Agriculture Reserarch Organisation
| Others |
| ARO | Airport Reporting Office
| Others |
| ARO | Airport Reservation Office
| Others |
| ARO | Alfa Romeo Owners
| Others |
| ARO | Algonquin Radio Observatory
| Others |
| ARO | Alpine Research Optics
| Others |
| ARO | Alternate Responsible Officer
| Others |
| ARO | Amateur Radio Operator
| Others |
| ARO | Analytics Research Organization
| Others |
| ARO | Animal Research
| Others |
| ARO | Animal Research Online
| Others |
| ARO | Animal Research Organization
| Others |
| ARO | Announcement of Research Opportunity
| Others |
| ARO | Annual Rate of Occurrence
| Others |
| ARO | Annual Report Online
| Others |
| ARO | Annualized Rate of Occurrence
| Others |
| ARO | Annualized Rate of Occurrence (ARO)
| Others |
| ARO | Anodizing Racks Online
| Others |
| ARO | Antibiotic Resistance Ontology
| Others |
| ARO | Antibiotic Resistant Organism
| Others |
| ARO | Antibiotic Resistant Organisms
| Others |
| ARO | Appliance Replacement Option
| Others |
| ARO | Application Resource Optimizer
| Others |
| ARO | Architecture Research Office
| Others |
| ARO | Architecture Research Offices
| Others |
| ARO | Arizona Radio Observatory
| Others |
| ARO | Army Radio Operator
| Others |
| ARO | Army Research Office
| Others |
| ARO | Aromantic
| Others |
| ARO | Art and Revolution Organization
| Others |
| ARO | Asset Retirement Obligation
| Others |
| ARO | Assisstant Review Officer
| Others |
| ARO | Assistant Review Officer
| Others |
| ARO | Associated Retail Operations
| Others |
| ARO | Association for Research in Otolaryngology
| Others |
| ARO | Association Resources Online
| Others |
| ARO | Atmospheric Research Observatory
| Others |
| ARO | Attribute Resolution Order
| Others |
| ARO | Austin Repeater Organization
| Others |
| ARO | Austin Rover Online
| Others |
| ARO | Auto Racing Outreach
| Others |
| ARO | Auto Repair Order
| Others |
| ARO | Autoliv Romania
| Others |
| ARO | Automatic Reconfiguration Order
| Others |
| ARO | Automatic Room Optimization
| Others |
| ARO | Automobilul Romanesc
| Others |
| ARO | Average Rating Of
| Others |
| ARO | Aviation Recreational Organization
| Others |