AOU

AOU may refer to:

• American Ornithologists' Union, former name of American Ornithological Society
• Apparent oxygen utilisation
• Arab Open University, private university
• Aou (trigraph)
• Age of Ultron, a 2013 series published by Marvel Comics
• Avengers: Age of Ultron, a 2015 superhero film of the same name by Marvel Studios

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