AOA is a three-letter abbreviation with multiple meanings, as described below:

• Administration on Aging, as AoA, an agency of the U.S. government
• Age of Apocalypse, an alternate timeline in the Marvel Universe, mostly involving the X-Men
• Airport Operations Area
• Alienating Our Audience, an album by New York band Mindless Self Indulgence.
• Alpha Omega Alpha, the national honor medical society in the United States and Canada
• American Optometric Association
• The American Osteopathic Association, the organization which oversees and accredits osteopathic medical schools in the United States
• Analysis of Alternatives, a report required by the United States Department of Defense on new weapon systems.
• Angle of Arrival, a technique for determining the direction of propagation of a radio-frequency wave incident on an antenna array.
• Angle of attack in aerodynamics
• The currency code for the Angolan kwanza
• AOA (band) a Japanese electronica project.
• Art of Ascension, a mod on the computer game Half-Life 2.
• Assalam-o-alaikum, Muslim greeting meaning "Peace be upon you"