AR

AR, Ar or ar may refer to:

• The letter R

Computing

• Abandonia Reloaded, a freeware games web community
• Accelerated Reader, educational reading assessment software
• Action Replay, video game device
• Activation record, a computer science term for the set of data regarding an active subroutine, stored within the stack
• Air Rivals, a MMORPG/FPS, the new Space Cowboy
• Alternate Reality, a primary racial trait in the 4X strategy computer game Stars!
• Armadillo Run, a physics-based, independently developed computer game
• ar (Unix), a Unix archive format and handling tool
• Aspect ratio (image), The relationship between the width and height of an image.
• Augmented reality, an application of virtual reality in the real world

Culture

• American Revolution
• Animal rights
• Argent, the heraldic tincture of silver
• Repair Ship, a U.S. Navy hull classification symbol
• ᛅ rune of the Younger Futhark
• Ar., an abbreviation related to Kodashim
• "Ar", a word in the West Country dialect of English, generally indicating agreement or assent and commonly associated with pirates.

Media

Music

• Abbey Road Studios, a recording studio
• Abbey Road, the eleventh album by The Beatles
• A&R a part of the music industry
• Artist and repertoire
• Atlantic Records
• A.R Rahman, Indian singer and music composer

Fiction

• Alex Rider, a fictional character and book series by author Anthony Horowitz
• Alternate reality, fictional concept
• Ar, largest city on the fictional planet Gor, in the novel series by John Norman
• Arlesdale Railway, a fictional railway in the Railway Series by W.V. Awdry
• Armaan and Riddhima, two lovebirds of the youthful show Dill Mill Gayye

Places

• .ar, the ccTLD for Argentina
• Argentina
• Arkansas, United States
• Ar (city), ancient Moab
• Appenzell Outer Rhodes, Switzerland
• Province of Arezzo, Italy
• Arad County, Romania
• Arunachal Pradesh, a state in north-eastern India

Publications

• Architectural Review, a publication of contemporary architecture
• Arizona Republic, a newspaper published in Phoenix, Arizona
• Absolute Return + Alpha, a hedge fund publication

Science

• Accelerated Rehabilitation
• Atomic Weight
• Adrenergic Receptor, a class of G protein-coupled receptors
• Analytical Reagent, a higher purity than SLR (Standard Laboratory Reagent)
• Androgen receptor, a nuclear hormone receptor
• Anti-reflective coating, a coating on lenses that allows better light transmission through the lens
• Aortic Regurgitation, a heart valve disease
• Archimedes number, in physics and engineering
• Argon, chemical symbol
• Artificial Respiration, a cardio-respratory technique for lifesaving
• Aryl functional group
• Autoregressive, stochastic process in econometrics
• Autosomal Recessive
• Silver, in numismatics

Other uses

• Alfa Romeo, automobile
• Ar. also used for salutation for Professional Architect
• AR-15, a rifle
• Accounts Receivable, an accounting term
• Assistant referee (association football)
• Arabic language (ISO 639 alpha-2 language code)
• Argentina (ISO 3166-1 alpha-2 country code)
• Autoregressive model, concerning random processes in statistics