| A&R | Advanced and Research 
| Others |
| A&R | Alert and responsive
| Others |
| A&R | Analysis and Reporting
| Others |
| A&R | Artists and Repertoire
| Others |
| A&R | Assembly and Repair
| Others |
| A&R | Automation and Robotics
| Others |
| A/R | Accounts Receivable
| Others |
| A/R | Alcohol-Related
| Others |
| A/R | As Required
| Others |
| AR | A Android Rickets
| Others |
| AR | abbreviates article
| Others |
| AR | Aberdeen and Rockfish Railroad
| Others |
| AR | Aberdeen and Rockfish Railroad Company
| Others |
| AR | Aboriginal Radio
| Others |
| AR | Abrasion Resistant
| Others |
| AR | Absolute Return
| Others |
| AR | Absorptive Region
| Others |
| AR | Abundance of Resources
| Others |
| AR | Academic Research
| Others |
| AR | Accelerated Reader
| Others |
| AR | Accelerated Readerar
| Others |
| AR | Accelerated Reading
| Others |
| AR | Accelerated Representer
| Others |
| AR | Accessible Radiation
| Others |
| AR | Acclerated Reading
| Others |
| AR | Account Receivable
| Others |
| AR | Account Review
| Others |
| AR | Account Reviews
| Others |
| AR | Accredited Reprocessor
| Others |
| AR | Acid Reflux
| Others |
| AR | Acoustic Research
| Others |
| AR | Acquisition Request
| Others |
| AR | Action Replay
| Others |
| AR | Action Request
| Others, Government |
| AR | Action Required
| Others |
| AR | Action Research
| Others |
| AR | Actionable And Realistic
| Others |
| AR | Active Rainfall
| Others |
| AR | Active Region
| Others |
| AR | Active Resistance
| Others |
| AR | Add Rows
| Others |
| AR | Added Rice
| Others |
| AR | Administrative Record
| Others |
| AR | Administrative Regulation
| Others |
| AR | Administrative Review
| Others |
| AR | Administrative Rules of the Superior Court
| Others |
| AR | Admitting Room
| Others |
| AR | Adult Reviews
| Others |
| AR | Adult Revolution
| Others |
| AR | Advance Retard
| Others |
| AR | Advance Revision
| Others |
| AR | Advanced Ring
| Others |
| AR | Adventure Racing
| Others |
| AR | Aerolíneas Argentinas
| Others |
| AR | Affix Rule
| Others |
| AR | Aged Residue
| Others |
| AR | Agricultural Residues
| Others |
| AR | Air Reconnaissance
| Others |
| AR | Air Refueling
| Others |
| AR | Air Route
| Others |
| AR | Airman Recruit
| Others |
| AR | Airworthiness Representative
| Others |
| AR | Alan Rickman
| Others |
| AR | Algae Resistant
| Others |
| AR | All Rail
| Others |
| AR | All Risks
| Others |
| AR | All The Right
| Others |
| AR | Allah Rakah
| Others |
| AR | Allah Rakha
| Others |
| AR | Allah-Rakha
| Others |
| AR | Aller-retour
| Others |
| AR | Alpha and Absolute Return
| Others |
| AR | Alphonso Rules
| Others |
| AR | Alternate Reality
| Others |
| AR | Alternative Response
| Others |
| AR | Aluminum Roofing
| Others |
| AR | Amateur Radio
| Others |
| AR | Amber Renee
| Others |
| AR | American Renaissance
| Others |
| AR | American Renegades
| Others |
| AR | American Revolution
| Others |
| AR | American Roadster
| Others |
| AR | Anal Retentive
| Others |
| AR | Analytical Reagent
| Others |
| AR | Andrew Riverside
| Others |
| AR | Androgen Receptor
| Others |
| AR | Animal Rights
| Others |
| AR | Anime Reactor
| Others |
| AR | Anna Regina
| Others |
| AR | Anna Rose
| Others |
| AR | Annihilation Radiation
| Others |
| AR | Anno Regni (Year of Reign)
| Others |
| AR | Annual Return
| Others |
| AR | Another Rainbow
| Others |
| AR | Anse Royale
| Others |
| AR | Anti Reflective
| Others |
| AR | Anti Reflux
| Others |
| AR | Anti-Reflective
| Others |
| AR | Antiwar Republican
| Others |
| AR | Any Road
| Others |
| AR | Aortic Regurge
| Others |
| AR | Aortic Regurgitation
| Others |
| AR | Apical Rate
| Others |
| AR | Apologetic Resources
| Others |
| AR | Apologetics Resources
| Others |
| AR | Appenzello Esterno
| Others |
| AR | Apple River
| Others |
| AR | Applied Research
| Others |
| AR | Applied Rule
| Others |
| AR | Approved Repair
| Others |
| AR | Approved Roofing
| Others |
| AR | Aqua Regia
| Others |
| AR | AR15 Rifle
| Others |
| ar | Arabic
| Others |
| AR | Archery Research
| Others |
| Ar | Archimedes number
| Others |
| Ar | Architect
| Others |
| Ar | Architecture
| Others |
| ar | Archiver
| Others |
| AR | Area Record
| Others |
| AR | Area Reference
| Others |
| AR | Arezzo (Provence)
| Others |
| ar | Argent
| Others |
| AR | Argentina
| Others |
| AR | Argentina AR
| Others |
| AR | Argon
| Element |
| AR | Argon AR
| Others |
| AR | Arithmetic Reasoning
| Others |
| AR | Arkansas
| State |
| AR | Arkansas Resident
| Others |
| AR | Arkansas Rom
| Others |
| AR | Arm Of Resistance
| Others |
| AR | ArmaLite
| Others |
| AR | Armalite Rifle
| Others |
| AR | Armalite Rifles
| Others |
| AR | Armand Rapha
| Others |
| ar | Armeerundschau
| Others |
| AR | Armilite Rifle
| Others |
| AR | Armor
| Others |
| AR | Army Regulation
| Others |
| AR | Army Regulation; Army Reserve
| Others |
| AR | Army Reserve
| Others |
| AR | Aromatic Ring
| Others |
| AR | Arretium
| Others |
| AR | Artificial Reality
| Others |
| AR | Artificial Respiration
| Others |
| AR | Artificial Resuscitation
| Others |
| AR | Artist and Repertoire
| Others |
| AR | Arunachal Pradesh
| State |
| Ar | Aryl group
| Others |
| AR | As Removed
| Others |
| AR | Aspect Ratio
| Others |
| AR | Assam Rifle
| Military, Army |
| AR | Assault Rifle
| Others |
| AR | Assault Rifle ( mostly american)
| Others |
| AR | Assessment Report
| Others |
| AR | Assistant Referee
| Others |
| AR | Assisted Respiration
| Others |
| AR | Asynchronous Request
| Others |
| AR | At Risk
| Others |
| AR | Atlantic Resolve (exercise name)
| Others |
| AR | Atlas Research
| Others |
| AR | Atmosphere Revitalization
| Others |
| AR | Atrophic Rhinitis
| Others |
| AR | Attack And Release
| Others |
| AR | Attack Rating
| Others |
| AR | Attempted Rape
| Others |
| AR | Attention Routine
| Others |
| AR | Audio Rate
| Others |
| AR | Audit Risk
| Others |
| AR | Augustus Rex
| Others |
| AR | Authority Representative
| Others |
| AR | Authorization Required
| Others |
| AR | Authorized Representative
| Others |
| AR | Autistic Referee
| Others |
| AR | Auto Regression
| Others |
| AR | Auto Regressive
| Others |
| AR | Automatic Rejection
| Others |
| AR | Automatic Remuneration
| Others |
| AR | Automatic Reset
| Others |
| AR | Automatic Rifle
| Others |
| AR | Autoregressive
| Others |
| AR | Average Reference
| Others |
| AR | Average Revenue
| Others |
| AR | Aylestone Road
| Others |
| Ar | Relative atomic mass
| Others |
| AR | Repair ship (Auxiliary, Repair)
| Others |
| AR | Romanian Academy
| Others |
| AR | The Architectural Review
| Others |
| AR | The Artificial Radionuclide
| Others |