AR

AR, Ar, or A&R may refer to:

• The letter R

Arts, entertainment, and media

Music

• A. R. Rahman, Indian singer and music composer
• Abbey Road, the eleventh album by The Beatles
• Abbey Road Studios, a recording studio
• Artists and repertoire, a division of a record label responsible for talent scouting and overseeing the development of artists or songwriters
• Atlantic Records, an American record label

Periodicals

• Absolute Return + Alpha, a hedge fund publication
• American Renaissance (magazine), a white nationalist magazine and website
• Architectural Review, a publication of contemporary architecture
• Arizona Republic, a newspaper published in Phoenix, Arizona
• Armeerundschau, a magazine of the East German army

Other media

• Ar, largest city on the fictional planet Gor, in the novel series by John Norman
• a.r. group, a group of Polish artists and poets, including Katarzyna Kobro and Julian Przyboś
• Abandonia Reloaded, a freeware games web community
• Alternate reality (disambiguation), a fictional concept

Businesses

• A & R Sales, a defunct firearms manufacturer
• Abbey Road Studios, a recording studio
• Aerolíneas Argentinas (IATA airline code AR)
• Alfa Romeo, an automobile brand
• Atlantic Records, an American record label
• Acoustic Research, an American audio electronics manufacturer

Language

• Ár, written "ᛅ", a rune of the Younger Futhark alphabet
• Arabic language (ISO 639 alpha-2 language code AR)

Mathematics, science, and technology

Computing

• ar (Unix), a Unix archive format and handling tool
• Accelerated Reader, educational reading assessment software
• Action Replay, a video game device
• Active record pattern
• Activation record, a computer science term for the set of data regarding an active subroutine, stored within the stack
• Aspect ratio (image), the relationship between the width and height of an image
• Augmented reality, an application of virtual reality in the real world

Biology and medicine

• Adrenergic receptor, a class of G protein-coupled receptors
• Adverse reaction, in pharmacy
• Androgen receptor, a nuclear hormone receptor
• Aortic regurgitation, a heart valve disease
• Artificial respiration, any means of assisting or stimulating respiration
• Autosomal recessive, in genetics

Mathematics

• Ar (function prefix) (area), a prefix of inverse hyperbolic functions
• Autoregressive model, concerning random processes in statistics

Physics and chemistry

• Analytical reagent, a chemical reagent with higher purity than Standard Laboratory Reagent
• Archimedes number, used to determine the motion of fluids due to density differences
• Argon, chemical element with symbol Ar
• Aryl, a functional group in organic chemistry
• Atomic radius
• Relative atomic mass

Other uses in mathematics, science, and technology

• AR-15, a rifle
• Anti-reflective coating, a coating on lenses that allows better light transmission through the lens
• Aspect ratio (wing), the relationship between the length and breadth (chord) of a wing
• Astronomer Royal, a post in the Royal Households of the United Kingdom

Military

• AR, the United States Navy hull classification symbol for "repair ship"
• Army Reserve (Ireland), the land component of the Irish Reserve Defence Forces (RDF)
• Army Ranger Wing also called Army Rangers, an Irish special operations force

Places

• Ar (city), in ancient Moab
• Appenzell Outer Rhodes, Switzerland
• Arad County, Romania
• Province of Arezzo, Italy
• Argentina (ISO 3166-1 alpha-2 country code)
  • .ar, the country code Top Level Domain for Argentina
• Arkansas, United States
• Arunachal Pradesh, India

Other uses

• Accelerated Rehabilitative Disposition, a pre-trial intervention program in the Commonwealth of Pennsylvania
• Accounts Receivable, in accounting
• American Revolution, a political upheaval between 1765 and 1783
• Arachin, in Judaism, one of 11 tractates of Kodashim, an order of the Mishnah
• Professional Architect, indicated by post-nominal letters "Ar."
• Argent, the heraldic tincture of silver
• Assistant referee (association football)
• Avis de réception (English: Advice or acknowledgment of receipt), a form of postal service
• Silver, in numismatics
• Augmented reality live view of a real-world environment whose elements are augmented or supplemented by computer-generated sensory input