AR

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

Music

 * Artists and repertoire
 * AR (EP), the debut EP by Addison Rae

Periodicals

 * Absolute Return + Alpha, a hedge fund publication
 * The Adelaide Review, an Australian arts magazine
 * American Renaissance (magazine), a white nationalist magazine and website
 * Architectural Review, a British architectural journal
 * Armeerundschau, a magazine of the East German army

Other media

 * Ar, city on the fictional planet Gor
 * A.r. group, an avant-garde art group
 * Alternate reality (disambiguation), various fictional concepts

Business

 * Accounts receivable, abbreviated as AR or A/R
 * Acoustic Research, an American audio electronics manufacturer
 * Aerojet Rocketdyne, an American aerospace and defense manufacturer
 * Aerolíneas Argentinas (IATA airline code AR)
 * AtkinsRéalis, Canadian engineering company
 * Some Alfa Romeo car models, e.g. AR51
 * Toyota AR engine

Language

 * Ar, the Latin letter R when spelled out
 * Ar (cuneiform), a cuneiform combined sign
 * Arabic, by ISO 639-1 language code

Computing

 * ar (Unix), a Unix archive format and handling tool
 * Accelerated Reader, educational reading assessment software
 * Augmented reality, an application of virtual reality in the real world
 * Adobe Aero, an Adobe software

Biology and medicine

 * Androgen receptor, a nuclear hormone receptor
 * Aortic regurgitation, a heart valve disease
 * Autosomal recessive inheritance

Mathematics

 * ar-, a prefix of inverse hyperbolic functions
 * Autoregressive model, concerning random processes in statistics

Physics and chemistry

 * Aqua regia, a chemical mixture
 * Archimedes number in fluid dynamics
 * Argon, symbol Ar, a chemical element
 * Aryl group in organic chemistry
 * Relative atomic mass, symbolized as Ar

Other uses in science and technology

 * Anti-reflective, coating of lenses
 * Aspect ratio (aeronautics), of a wing

Military and weapons

 * A US Navy hull classification symbol: Repair ship (AR)
 * Armalite Rifle
 * AR-15–style rifle, rifles based on ArmaLite's AR-15
 * Army Reserve (Ireland), the land component of the Irish Reserve Defence Forces (RDF)

Places

 * Ar (city), in ancient Moab
 * Appenzell Ausserrhoden, Switzerland
 * Province of Arezzo, Italy, vehicle registration code
 * Argentina (ISO 3166-1 alpha-2 country code)
 * .ar, the country code Top Level Domain for Argentina
 * Arkansas, United States
 * Armstrong–Ringsted Community School District, Iowa, United States
 * Arunachal Pradesh, a state of India

Politics and ethics

 * Affirmative Repositioning, a political movement in Namibia
 * Animal rights, a philosophy
 * Animal rights movement, a social movement advocating for other animals
 * Antipodean Resistance, an Australian neo-Nazi group

Other uses

 * 🜇 or AR, a numismatic abbreviation for "silver"
 * Argent, the heraldic tincture of silver
 * Assistant referee (association football)
 * Auto rickshaw, a motorized three-wheeled vehicle common in South Asia
 * Avis de réception, postal advice or acknowledgement of receipt