# AC

AC, A.C., A/C, or Ac often refers to:
* Air conditioning, often abbreviated as A/C
* Alternating current, a type of electrical current in which the current repeatedly changes direction
AC, A.C. or Ac may also refer to:

## Arts and entertainment
### Gaming

* Ace Combat, a series of combat flight simulator games
* Animal Crossing, a series of community simulation games
* Anonymous;Code, a visual novel in the Science Adventure series
* Another Code, a series of adventure games
* Armored Core, a series of mecha-based third person shooter games
* Asheron's Call, a fantasy massively multiplayer online role-playing game
* Assassin's Creed, a series of action-adventure games
* Assetto Corsa, a racing simulator game
* Astral Chain, an action-adventure hack and slash game
* Armor Class, a combat-related parameter in the Dungeons & Dragons role playing game system
* A.C., a character in Fortnite: Save the World

### Music

* A.C. Newman, solo stage name for Canadian musician Carl Newman
* AC/DC, an Australian rock band formed in Sydney in 1973
* Adult contemporary music, a genre description used mainly in radio broadcasting
* Adult Contemporary (chart)
* Anal Cunt, an American musical group

### Other media

* AC Comics, a comic book publisher established in 1969
* A.C. Slater, a fictional character in the American sitcom Saved by the Bell
* After Colony, an alternate timeline in the Gundam metaseries for the universe of Gundam Wing
* AC, the name of the "ultimate computer" in Isaac Asimov's novel The Last Question
* Asianovela Channel, a defunct Filipino TV channel

## Organizations
### Businesses

* AC Cars, a British specialist automobile manufacturer
* AC Spark Plug, Delco, AC-Delco, and ACDelco, automotive parts brands owned by General Motors
* AC Hotels, a hotel chain owned by Marriott International
* AC Restaurants, a hotel and restaurant chain in the Benelux
* Air Canada, the flag carrier and largest airline of Canada (IATA code AC)
* Allis-Chalmers, a former industrial conglomerate
* Anderson, Clayton and Company, former American cotton trading firm
* Associated Content, an online publisher and distributor of original content
* Ayala Corporation, a holding company (Philippine Stock Exchange symbol AC)

### Politics

* Action Congress, a political party in Nigeria
* Advisory Council on Youth, a non-governmental decision-making body in the Council of Europe.
* Alternative for Change (Alternativa por el Cambio), a political party in Nicaragua
* Coast Alliance (Alianza Costeña), a former regional political coalition in Nicaragua

### Other organizations

* AC – The Danish Confederation of Professional Associations, an umbrella organisation for several Danish trade unions
* AC Transit, a regional public transit agency in the San Francisco Bay Area
* Ad Council Japan (AC Japan), an organization that distributes Japanese public service announcements
* Athletics Canada, the governing body of athletics in Canada
* Civic Alliance Foundation (Alianţa Civică), a Romanian non-governmental organization
* Anthrocon, the second largest furry convention in the world, held in Pittsburgh, Pennsylvania, US
* Audit Commission (Hong Kong), a government department in Hong Kong Special Administrative Region
* Aryan Circle, a white supremacist, Neo-Nazi prison gang spread throughout many U.S. correctional facilities

## People

* AC Bonifacio (born 2002), a Philippine-Canadian actress, singer and dancer
* A.C. Green (born 1963), retired professional basketball player
* A. C. Grayling (born 1949), British philosopher
* Al Cowlings (born 1947), retired American football player

## Places

* .ac, Internet top-level domain name for Ascension Island
* Aachen, a spa town in North Rhine-Westphalia, Germany
* Acre (state), Brazil
* Aleksandrovac, Serbia (vehicle registration plate code AC)
* Antigua and Barbuda, obsolete two-letter FIPS and NATO codes
* Atlantic City, New Jersey, US

## Ranks, titles, and awards

* Aelod y Cynulliad, title for Members of the National Assembly for Wales
* Aircraftman, an air forces rank
* Ashoka Chakra (military decoration), India's highest peacetime military decoration
* Assistant Commissioner of Police of the Metropolis, a rank in London's Metropolitan Police
* Companion of the Order of Australia
* First assistant camera or Second assistant camera, in film-making
* Aviation Cadet, a military rank sometimes written as A/C

## Science and technology
### Biology and medicine

* Acromioclavicular joint (AC joint), the shoulder junction between the scapula and the clavicle
* Adenylate cyclase, a lyase enzyme
* Adriamycin and cyclophosphamide, a chemotherapy regimen used to treat breast cancer
* Ante cibum (ac), Latin for "before meal", commonly seen in medical prescriptions
* Anterior commissure, a bundle of nerve fibers connecting the two temporal lobes of the brain
* Anterior cruciate ligament (AC ligament or ACL), a major ligament in the knee
* Appropriateness criteria, when it is appropriate to perform a medical procedure or service
* Assist control, a former term for continuous mandatory ventilation, a mode of mechanical ventilation
* Adenocarcinoma, a type of cancerous tumor
* Allergic conjunctivitis, inflammation of the conjunctiva

### Chemistry

* Acetyl, a functional group in chemistry
* Actinium, symbol Ac, a chemical element
* Hydrogen cyanide, also called as AC in chemical weapon term

### Computing and telecommunications

* .ac, Internet top-level domain name for Ascension Island
* .ac (second-level domain), Internet second-level domain used to denote academic institutions in many countries
* AC (complexity), a hierarchy of complexity classes found in circuit complexity
* AC, initialism of access control
* Artificial consciousness, a field related to artificial intelligence and cognitive robotics
* Authorization certificate or attribute certificate, a digital permission to use a service or resource
* Arithmetic coding, a form of entropy encoding used in lossless data compression
* alternating component a.k.a. AC coefficient in discrete cosine transform
* IEEE 802.11ac, a wifi standard using 5 GHz, released in Dec 2013

### Meteorology

* Altocumulus, a medium level cloud type
* Anticipated convection, convective outlooks issued by the U.S. National Weather Service

### Other uses in science and technology

* Air conditioning, technologies for altering the temperature and humidity of air
* Across corners (A/C), a measure of external diameter of hexagonal nuts
* Alternating current, a type of electric current
** AC power, a net transfer of energy over a complete cycle of the alternating current waveform
* Asphalt concrete, a type of road or path surfacing
* Average cost, in economics
* Axiom of choice, a mathematical concept in set theory
* A US Navy hull classification symbol: Collier (AC)

## Other uses

* Ac (rune) (ᚪ), a rune of the Anglo-Saxon fuþorc and a continuation of the Elder Fuþark ansuz
* Abkhazian Cup, football cup competition in Abkhazia
* A.C. Milan, an Italian football club based in the city of Milan
* Acre, a unit of area with the symbol ac
* Advisory circular, a publication to provide guidance for compliance with airworthiness regulations
* Ante Christum or A.C., a Latin term meaning "before Christ"
* Antichrist, a Biblical prophecy about one who will oppose Jesus Christ and substitute himself in Christ's place
* Appeal Cases, or A.C., a UK law reporter covering decisions of the House of Lords, Supreme Court, Privy Council, and Court of Appeal
* Ards Circuit, motorsport racing circuit
* Armor Class, a common property in role playing games used to determine the amount of armor a character has
* Army Corps, an operational formation, sometimes known as a field corps, which consists of two or more divisions
* Atlantic College, an international IB Diploma Programme residential Sixth Form College in the Vale of Glamorgan in Wales
* Auto Calesa, a war-time short-body version of the Philippine jeepney