AO

AO, aO, Ao, or ao may refer to:

Science and technology

.ao, top-level Internet domain code for Angola
Adaptive optics, an astronomical imaging technology
AO Foundation (originally Arbeitsgemeinschaft für Osteosynthesefragen), a non-profit organisation dedicated to the treatment of trauman and disorders of the musculoskeletal system
Arctic oscillation, a climate pattern
AMSAT-OSCAR, a satellite naming convention
Applied Optics, scientific journal published by the Optical Society of America (OSA)

Angola, ISO code and NATO country code AO
Autonomous oblast or autonomous okrug, types of Russian administrative divisions
Administrative Office of the United States Courts
NSDAP/AO, Foreign Organization branch of the Nazi Party
Officer of the Order of Australia, postnominal AO

Ao (color)
Ao (mythology), a deity in Māori mythology
Ao (turtle), a creature in Chinese mythology
Ao Naga, an Indian ethnic group
Ao languages
Aaron Owens (born 1976), American streetball player
Area of operations, a U.S. military term
Australian Airlines, IATA code AO
AO, Alpha and Omega (abbreviation)
Ao, an ancient Polynesian word for light or daytime
Ao, a type of Easter Island wood carving
AO, a U.S. Navy hull classification symbol for an oiler
AO-, the prefix for several firearms
Athletics Ontario, formally Ontario Track and Field Association (OTAF)
Aktsionernoye Obschestvo, a Russian corporate entity similar to a joint-stock company
Aviation Ordnanceman, a United States Navy occupational rating
ao, außerordentlicher, e.g. ao Prof., "Professor extraordinarius"