| A&O | Alert and Orientated 
| Others |
| A&O | Alert and Oriented
| Others |
| A&O | Aware and Oriented
| Others |
| A/O | Acceptance of Order
| Others |
| A/O | Age at Onset
| Others |
| a/o | and/or
| Others |
| A/O | Area Of
| Others |
| A/O | At Once
| Others |
| AO | Abdominal Obesity
| Others |
| AO | Academic Office
| Others |
| AO | Accepted Offer
| Others |
| AO | Access Orlando
| Others |
| AO | Accompaniment Only
| Others |
| AO | Account Of
| Others |
| AO | Accountable Officer
| Others |
| AO | Accreditation Organisation
| Others |
| AO | Accrediting Organization
| Others |
| AO | Acid Output
| Others |
| AO | Acousto Optic
| Others |
| AO | Acridine Orange
| Others |
| AO | Acronym Or
| Others |
| AO | Action Office
| Others |
| AO | Adaptive Optics
| Others |
| AO | Adjustable Objective
| Others |
| AO | Administratieve Organisatie
| Others |
| AO | Administration Officer
| Others |
| AO | Administrative Occupations
| Others |
| AO | Administrative Officer
| Others |
| AO | Administrative Ownership
| Others |
| AO | Adult Onset
| Others |
| AO | Adults Only
| Others |
| AO | Advanced Optics
| Others |
| AO | Adverse Outcome
| Others |
| AO | Aerial Observer
| Others |
| AO | Aesthetic Objective
| Others |
| AO | Aesthetic Olympian
| Others |
| AO | Age of Onset
| Others |
| AO | Agent Orange
| Others |
| AO | Air Observer
| Others |
| AO | Air Officer
| Others |
| AO | Airport Operations
| Others |
| AO | Airways Obstruction
| Others |
| AO | Aktsionernoye Obshestvo
| Others |
| AO | Aldehyde Oxidase
| Others |
| AO | All Off
| Others |
| AO | All Other
| Others |
| AO | All Outdoors
| Others |
| AO | All Output
| Others |
| AO | All The Other
| Others |
| AO | Alon Oleartchik, musician
| Others |
| AO | Alpha Omega
| Others |
| AO | Alpha Oscillator
| Others |
| AO | Alpha Out
| Others |
| AO | Alternative Option
| Others |
| AO | Alternative Ordinary
| Others |
| AO | Altogether Outdoors
| Others |
| AO | Alveolar Osteitis
| Others |
| AO | Always Open
| Others |
| AO | Always Oscillating
| Others |
| AO | Amateur Owner
| Others |
| AO | Ambient Occlusion
| Others |
| AO | American Optical Company
| Others |
| AO | American Overseas
| Others |
| AO | Among Others
| Others |
| AO | Amount Of ....
| Others |
| AO | Anal Orfice
| Others |
| AO | Analog Out
| Others |
| AO | Analog Output
| Others |
| AO | Anaplastic Oligodendroglioma
| Others |
| AO | Anarchy Online
| Others |
| AO | Ancient One
| Others |
| AO | and AO
| Others |
| AO | Angelic Oceans
| Others |
| AO | Angle Of
| Others |
| AO | Angle Of ....
| Others |
| AO | Angola
| Others |
| AO | Angola AO
| Others |
| AO | Angry Outburst
| Others |
| AO | Anime Online
| Others |
| AO | Ankle Orthosis
| Others |
| AO | Annotated Outline
| Others |
| AO | Announcement of Opportunity
| Others |
| AO | Annoying Orange
| Others |
| AO | Anonim Ortaklik
| Others |
| AO | Another One
| Others |
| AO | Anterior Oblique
| Others |
| AO | Anthony Oropeza
| Others |
| AO | Anti-Oxidant
| Others |
| AO | AntiOxidant
| Others |
| AO | Antique and Old
| Others |
| AO | Antiquites Orientales
| Others |
| AO | Antisense Oligonucleotide
| Others |
| AO | Aoiro Ohki
| Others |
| AO | Aorta
| Others |
| AO | Aortic Occlusion
| Others |
| AO | Aortic Opening
| Others |
| AO | Aosta (Province)
| Others |
| AO | Apoctalyptic Order
| Others |
| AO | Appalachian and Ohio Railroad
| Others |
| AO | Application Object
| Others |
| AO | Approval Order
| Others |
| AO | Aqueous Oxygen
| Others |
| AO | ARC Objects
| Others |
| AO | Arctic Oscillation
| Others |
| AO | Area of Operation
| Others |
| AO | Area of Operations
| Others |
| AO | Arentzen Ohlander Glass Studio
| Others |
| AO | Argentum Online
| Others |
| AO | Army Orders
| Others |
| AO | Arterial Occlusion
| Others |
| AO | Aspheric Optics
| Others |
| AO | Ass Ole
| Others |
| AO | Assembling Objects
| Others |
| AO | Assembly Order
| Others |
| AO | Assessing Officer
| Others |
| AO | Assessment Objective
| Others |
| AO | Assessment Objectives
| Others |
| AO | Associate Post Office
| Others |
| AO | Associated Operations
| Others |
| AO | Assured Outcomes
| Others |
| AO | Astromanialetta Orphormotogus
| Others |
| AO | Astronomical Observatory
| Others |
| AO | Athol Orange
| Others |
| AO | Atlantic Ocean
| Others |
| AO | Atlanto-Occipital
| Others |
| AO | Atlanto-Odontoid
| Others |
| AO | Atomic Orbital
| Others |
| AO | Atomic Oxygen
| Others |
| AO | Attribute On
| Others |
| AO | Atypical Odontalgia
| Others |
| AO | Aubrey Organics
| Others |
| AO | Audi Only
| Others |
| AO | Audi Option
| Others |
| AO | Australian Airlines
| Others |
| AO | Australian Open
| Others |
| AO | Authorize Only
| Others |
| AO | Authorized Occupant
| Others |
| AO | Authorizing Official
| Others |
| AO | Auto Off
| Others |
| AO | Auto Ordnance
| Others |
| AO | Automags Online
| Others |
| AO | Automatic Metal Products
| Others |
| AO | Autonomous Object
| Others |
| AO | Autres Objets (other articles)
| Others |
| AO | Auxiliary Office
| Others |
| AO | Auxiliary Oiler
| Others |
| AO | Auxiliary Operator
| Others |
| AO | Auxillary Oiler
| Others |
| AO | Average of OC
| Others |
| AO | Aviation Officer
| Others |
| AO | Aviation Ordnance
| Others |
| AO | Aviation Ordnanceman
| Others |
| AO | Aviatsionnaya Oskolochnaya
| Others |
| AO | Aviatsionnaya Oskolochnyang (aircraft fragmentation ammunition)
| Others |
| AO | Fleet Oiler (Auxiliary, Oiler)
| Others |
| AO | Liga Comunista - Acuerdo Obrero
| Others |
| AO | Officer of the Order of Australia
| Others |