AAR may mean:

• An abbreviation for the English phrase "at any rate."
• An abbreviation found in the insurance industry, for "against all risks."
• An abbreviation used in certain strategy game discussions about given game history and player perfomance, for "after action report "
• An abbreviation for the military mission of Aerial refueling
• The Aar, also known as the Aare, a river in Switzerland
• The IATA airport code for Aarhus Airport, Denmark
• The Association of American Railroads
• The ISO 639 code for the Afar language
• An acronym for the band The All-American Rejects