AD (Anno Domini) is a designation used to label years following 1 BC in the Julian and Gregorian calendars.
Ad (advertisement) is a form of marketing communication.
AD, A.D. or Ad may also refer to:
Art, entertainment, and media
Film and television
- A.D. (film), a 2010 animated zombie horror film
- A.D. (miniseries), a 1985 television miniseries set in ancient Rome
- A.D. The Bible Continues, a 2015 biblical drama television miniseries
- Arrested Development, an American television sitcom
- Attarintiki Daredi, 2013 Indian film by Trivikram Srinivas
- Audio description, a service for visually impaired audience on some TV programs
Music
- AD (band), a Christian rock band
- A.D. (album), by Solace
Publications
- AD (poem), by Kenneth Fearing
- A.D.: New Orleans After the Deluge, a nonfiction graphic novel about Hurricane Katrina
- Algemeen Dagblad, a Dutch newspaper
- Architectural Digest, an interior design and landscaping magazine
Other art, entertainment, and media
- Audio description track, a narration track for visually impaired consumers of visual media
Brands and enterprises
- Alexander Dennis, a British bus manufacturer
- Akcionersko društvo (aкционерско друштво), a Macedonian name for a type of company
- Aktsionerno drujestvo (акционерно дружество), a Bulgarian name for a type of company
- akcionarsko društvo (aкционарско друштво), a Serbian name for a type of company
- Analog Devices, a semiconductor company
Educational qualifications
- Artist diploma, a music performance certificate conferred by higher education institutions.
Military
- Accidental discharge, a mechanical failure of a firearm causing it to fire
- Active duty, a status of full duty or service, usually in the armed forces
- Air defense, an anti-aircraft weaponry and systems
- Air Department, part of the British Admiralty
- A US Navy hull classification symbol: Destroyer tender (AD)
- AD Skyraider, former name of the Douglas A-1 Skyraider, a Navy attack aircraft
Organizations
- Action Directe, a French far-left militant group
- Democratic Action (Venezuela) (Spanish: Acción Democrática), a social democratic and center-left political party
- Democratic Alliance (Portugal, 1979) (Portuguese: Aliança Democrática), a former centre-right political alliance
- Democratic Alternative (Malta) (Maltese: Alternattiva Demokratika), a green political party
People
- Ad (name), a given name, and a list of people with the name
- ‘Ad, great-grandson of Shem, son of Noah
- Anthony Davis (born 1993), American basketball player
- A. D. Loganathan (1888–1949), officer of the Indian National Army
- A. D. Whitfield (born 1943), American football player
- A. D. Winans (born 1936), American poet, essayist, short story writer and publisher
- A.D., nickname of Adrian Peterson (born 1985), American football player
Places
- AD, ISO 3166-1 country for Andorra
- Abu Dhabi, capital of the United Arab Emirates
- AD, herbarium code for the State Herbarium of South Australia
- Andhra Pradesh, a state in southern India (HASC code)
Professions
- Art director, for a magazine or newspaper
- Assistant director, a film or television crew member
- Athletic director, the administrator of an athletics program
Science and technology
Biology and medicine
- Addison's disease, an endocrine disorder
- Adenovirus, viruses of the family Adenoviridae
- Alzheimer's disease, a neurodegenerative disease
- Anaerobic digestion, processes by which microorganisms break down biodegradable material
- Anti-diarrheal, medication which provides symptomatic relief for diarrhea
- Aortic dissection, which occurs when an injury to the innermost layer of the aorta allows blood to flow between the layers of the aortic wall, forcing the layers apart
- Approximate digestibility, an index measure of the digestibility of animal feed
- Atopic dermatitis, form of skin inflammation
- Atypical depression, a type of depression
- Autosomal dominant, a classification of genetic traits
- Autonomic dysreflexia, a potential medical emergency
Chemistry
- Adamantyl, abbreviated "Ad" in organic chemistry
- Sharpless asymmetric dihydroxylation, a type of organic chemical reaction
Computing
- .ad, the top level domain for Andorra
- Administrative distance, a metric in routing
- Active Directory, software for the management of Microsoft Windows domains
- Administrative domain, a computer networking facility
- Analog-to-digital converter, a type of electronic circuit
- Automatic differentiation, a set of computer programming techniques to speedily compute derivatives
- AD16, the hexadecimal number equal to decimal number 173
Mathematics
- Adjoint representation of a Lie group, abbreviated "Ad" in mathematics
- Axiom of determinacy, a set theory axiom
Physics
- Antiproton Decelerator, a device at the CERN physics laboratory
- Autodynamics, a physics theory
Other uses in science and technology
- Active disassembly, a technology supporting the cost-effective deconstruction of complex materials
Transportation
- AD, IATA code for:
- Air Paradise, a defunct Indonesian airline
- Azul Brazilian Airlines
- Airworthiness Directive, an aircraft maintenance requirement notice
Other uses
- ʿĀd, an ancient Arab tribe, mentioned in the Quran
- Aggregate demand, in macroeconomics
- Anno Diocletiani, an alternative year numbering system
- United States Academic Decathlon, a high school academic competition