ATR may refer to:

• Acute transfusion reaction
• Ataxia telangiectasia and Rad3 related, a protein involved in DNA damage repair

• Advanced Test Reactor, nuclear research reactor at the Idaho National Laboratory, US
• Attenuated total reflectance in infrared spectroscopy
• Advanced tongue root, a phonological feature in linguistics
• Atractyloside, a toxin and inhibitor of "ADP/ATP translocase"
• ATR₀, an axiom system in reverse mathematics

• Answer to reset, a message output by a contact Smart Card
• Automatic target recognition, recognition ability
• Autothermal reforming, a natural gas reforming technology

• ATR (aircraft manufacturer) an Italian-French aircraft manufacturer
  • ATR 42 airliner
  • ATR 72 airliner
• IATA code for Atar International Airport
• Andaman Trunk Road
• Air Transport Rack, standards for plug-in electronic modules in aviation and elsewhere; various suppliers e.g. ARINC
• Atmore (Amtrak station), Amtrak station code ATR

• All That Remains (band), an American heavy metal band
• Atari Teenage Riot, a German techno band performing "digital hardcore" music
  • ATR (song), a song by ATR

• Absent Teacher Reserve, of teachers in New York City
• Americans for Tax Reform
• Anglican Theological Review

• African Traditional Religion
• A US Navy hull classification symbol: Rescue tug (ATR)
• ATR: All Terrain Racing, a video game
• ATR.1 certificate, in trade between the European Union and Turkey
• ATR (company) (Auto-Teile-Ring), Germany
• Average True Range, a market volatility indicator
• ATR (TV channel), a Crimean Tatar television channel in Ukraine

This disambiguation page lists articles associated with the title ATR.
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