AR

AR, Ar or ar can mean:

*the letter R

Places, regions, languages

*.ar, the ccTLD for Argentina;
*Appenzell Outer Rhodes, Swiss canton;
*Arabic language (ISO 639 alpha-2 language code);
*Argentina, ISO 3166-1 alpha-2 and FIPS 10-4 digram country code;
*Arkansas (United States postal abbreviations);

Music

*Abbey Road Studios, a recording studio.
*"Abbey Road", the twelfth album by The Beatles.

Medicine, technology, science, mathematics, economics

*Relative atomic mass;
*Adrenergic Receptor, a class of G protein-coupled receptors;
*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;
*Analytical Reagent, such as Zinc acetate, Mandelic acid or Perchloric acid;
*AR-15, a popular Assault Rifle;
*Argon, chemical symbol;
*Armalite, maker of the AR-15, a popular Assault Rifle;
*Artificial Respiration, a cardio-respratory technique for lifesaving;
*Artist and repertoire
*Autoregressive, stochastic process in Econometrics;
*Silver, in the field of numismatics (from the Latin Argentum);

Computer related

*ar is a Unix archive format and handling tool;
*Accelerated Reader, educational reading assessment software;
*Activation record, a computer science term for the set of data regarding an active subroutine, stored within the stack;
*Augmented reality, an application of virtual reality in the real world;

Computer games

*Abandonia Reloaded, a freeware games web community;
*Action Replay, Video game device;
*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;

Businesses, organizations, groups, publications

*A&R a part of the music industry;
*Acoustic Research, a brand name of Audiovox;
*Aberdeen and Rockfish Railroad, (AAR reporting mark);
*Aerolíneas Argentinas, IATA airline designator;
*Architectural Review, a publication of contemporary architecture;
*"Arizona Republic", a newspaper published in Phoenix, Arizona;
*Armalite, an American arms manufacturer (e.g. AR-15 or any rifle of the same pattern);
*Atlantic Records;

Culture and history

*Accounts Receivable, an accounting term;
*American Revolution;
*Animal Rights, among animal rights activists;
*Ar - Ancient Armenia the Ar was the god Sun;
*Argent, the heraldic tincture of silver;
*Repair Ship, U.S. Navy hull classification symbol;
*the ᛅ rune of the Younger Futhark;

Fiction

*Alex Rider, a fictional book series, by author, Anthony Horowitz; and the character with the same name;
*Ar, largest city on the fictional planet Gor, in the Gorean series by John Norman;
*Arlesdale Railway, a fictional railway in the Railway Series by W.V. Awdry;