Ada or ADA may refer to:

People

• St. Ada, a 7th-century French abbess.
• Ada, Countess of Atholl (died 1264)
• Ada, Countess of Holland
• Ada de Warenne, Countess of Northumbria and Huntingdon (d. 1178)
• Ada of Caria, satrap deposed by her brother Idrieus and restored by Alexander the Great
• Ada, sister of Charlemagne, for whom the Ada Gospels at Trier were produced
• Variant transliteration of Hebrew Adah (עָדָה)
• Ada Lovelace, daughter of Lord Byron, recognized as the first computer programmer

Places

• Ada, Ghana
• Ada, Serbia
• Ada County, Idaho, U.S.
• Ada, Minnesota, U.S.
• Ada, Ohio, U.S.
• Ada, Oklahoma, U.S.
• Ada Township, Michigan, U.S.
• Ada River, New Zealand

Media

Television and film

• Ada (film), a 1961 film directed by Daniel Mann, with Susan Hayward and Dean Martin
• ADA...A Way of Life, a 2008 Bollywood musical directed by Tanvir Ahmed
• Ada (dog actor), who played Colin on the sitcom Spaced

Books

• Ada or Ardor: A Family Chronicle, a 1969 novel by Vladimir Nabokov

Video games

• Ada (Castlevania), a character from the video game Castlevania: Legacy of Darkness
• Ada Wong, a character from the video games Resident Evil 2 and Resident Evil 4
• ADA, a character in the Zone of the Enders video game franchise

Music

• Alternative Distribution Alliance, a music distributor owned by Warner Music Group

Politics and government

• Americans with Disabilities Act of 1990
• Aeronautical Development Agency of India's Ministry of Defence
• Air Defense Artillery, a branch of the United States Army
• Americans for Democratic Action, anticommunist liberal lobby
• Amazon Development Agency (Agência de Desenvolvimento da Amazônia), a development agency in Brazil
• Assistant district attorney, a staff member under a district attorney

Air travel

• Aerolínea de Antioquia, a Colombian Airline
• Airline Deregulation Act, a 1978 US bill removing governmental control from commercial aviation
• The IATA code for International Adana Şakirpaşa Airport in Adana, Turkey

Science and technology

Physics

• AdA, or L'Anello di Accumulazione, was the first particle collider.

Computing

• Ada (programming language), a programming language based on Pascal
• Ada (computer virus), a memory resident, file infecting computer virus which infects COM files

Medicine

• American Dental Association
• American Diabetes Association
• American Dietetic Association

Enzymes

• Adenosine deaminase, an enzyme involved in purine metabolism
• Ada (protein), an enzyme induced by treatment of bacterial cells

Botany

• Ada (orchid), a genus of orchids

Other

• Adangme language, a Kwa language spoken in south-eastern Ghana
• Advanced Distribution Automation, the extension of intelligent control over an electrical power grid
• Amigos dos Amigos, one of the three main drug cartels in the favelas of Rio de Janeiro
• American Decency Association, a non-profit Christian right organization
• Aqua Design Amano, Takashi Amano's aquarium product line
• Association of Drainage Authorities, a membership body for those involved in water level management in the United Kingdom

See also

• Ada Township