AAR

AAR or Aar may refer to:

Geography

 * Aar, a river in Switzerland, tributary of the Rhine
 * Aar (Lahn), a tributary of Lahn river in Germany, descending from the Taunus mountains
 * Aar (Dill), a tributary of Dill river in Germany, also in the basin of the Lahn
 * Aar (Ill), a branch of the Ill river that separates from it in Strasbourg, France and rejoins it further north
 * Aar (Twiste), a tributary of Twiste river in Germany, in the basin of the Weser
 * Aar (village), a village in Rajasthan, India
 * South American–Antarctic Ridge, also known as the American–Antarctic Ridge, a mid-ocean ridge in the South Atlantic
 * Antarctica, IAAF code AAR

Military

 * After-action review, a structured review process used by the U.S. military
 * After action report, a retrospective analysis
 * Air-to-air refueling, the process of transferring aviation fuel from one military aircraft to another during flight
 * Assistant Automatic Rifleman, a soldier who carries ammunition, see Rifleman.

Organizations

 * All American Racers, a former Formula 1 and CART team
 * Allens (law firm), a law firm (formerly known as Allens Arthur Robinson)
 * American Academy in Rome, research and arts institution in Rome
 * American Academy of Religion, an association of academics who research or teach topics related to religion
 * Association for Automated Reasoning, a non-profit that seeks to advance the field of automated reasoning
 * Association of American Railroads, an industry trade group representing the railroads of North America

Transportation

 * AAR Corporation, an American aviation engineering company
 * AAR coupling, railway coupling specification of the Association of American Railroads
 * AAR wheel arrangement, Association of American Railroads system for describing wheel arrangement of locomotives
 * All-American Road, a designation for some national scenic byways in the United States
 * Ann Arbor Railroad (disambiguation)
 * IATA airport code for Aarhus Airport in Tirstrup, Denmark
 * ICAO airline code for Asiana Airlines of South Korea

Other uses

 * Aar (Star Wars), fictional planet in Star Wars universe
 * Aar, a fictional planet of the star Deneb, in the "Captain Future" stories
 * The All-American Rejects, an American rock band
 * Air America Radio, a domestic United States radio network
 * Average accounting return, a capital budgeting investment rule
 * Adam's apple reduction, a surgery
 * Afar language (ISO 639 language identification code)
 * African American Review, a journal
 * Amino acid response, the biochemical response of a mammalian cell starved of amino acids
 * "At any rate", see List of SMS abbreviations
 * Alkali–aggregate reaction, a chemical reaction leading to expansion in concrete