AC

Science

Actinium (Ac), a chemical element
Acetaldehyde (Ac), an organic ion
Acetate (Ac), an organic ion
Acetyl (Ac), a functional group in chemistry
Acromioclavicular joint in humans and other animals, frequently injured in sport
Adenylate cyclase, an enzyme
Chemotherapy regimens, Adriamycin and cyclophosphamide, a chemotherapy regimen used to treat breast cancer
Alpha Centauri, a star system in the constellation Centaurus
Alternating current, a type of electric current
AC power, a net transfer of energy over a complete cycle of the alternating current waveform
Animal communication
Anterior commissure, a small bundle of nerve fibres that connect the right and left temporal lobes
Anticipated convection, the code for severe thunderstorm forecasts issued daily for the contiguous U.S. by the Storm Prediction Center
Power cable#Named cable types, a type of power cable used by electricians
Artificial consciousness
Astrographic Catalogue, a star catalogue
Axiom of choice, a mathematical set theory concept

Places

Aachen, Germany, uses the number plate code AC
Acre (state), Brazil, is abbreviated AC
Västerbotten County, Sweden
Atlantic City, New Jersey

Computing

Accumulator (computing), a register in the CPU that stores intermediate ALU results
AC (complexity), a hierarchy of complexity classes found in circuit complexity
.ac, Internet top-level domain name for Ascension Island
.ac (second level), Internet second-level domain used to denote academic institutions in many countries
Anonymous Coward, in the Slashdot online environment
Arctic Cooling, a Swiss manufacturer of heatsinks, cooling fans and computer cases
Authorization certificate or attribute certificate, a digital permission to use a service or resource
Auto clickers, in the MMORPGs gaming community

Job titles / ranks

A person appointed Companion Of The Order Of Australia
Aelod y Cynulliad, the title for Members of the National Assembly for Wales
Aircraftman
Assistant Commissioner of Police of the Metropolis

Sports

A.C. Milan, one of the most successful Italian clubs
America's Cup
Athletic Club, full name of Athletic Bilbao

Entertainment

AC, the name of the ultimate computer at the end of time in Isaac Asimov's The Last Question
After Colony, an alternate timeline in the Gundam metaseries for the universe of Gundam Wing
Albert Clifford "A.C." Slater, a character in the American sitcom Saved by the Bell
"Alt Cataclius" or "After Cataclysm", a historical era in the timeline for the Dragonlance fictional universe
Arthur Curry, who goes by his initials during an appearance on Smallville
Armor Class, a combat-related parameter in the Dungeons & Dragons role playing game system
Final Fantasy VII Advent Children, a movie sequel to the game Final Fantasy VII

Video games

Ace Combat, a series of combat flight simulator games
Alliance Character as used by Horde players in the MMORPG World of Warcraft
Animal Crossing (series), a series of real-time village simulations by Nintendo
Armored Core, a series featuring the eponymous robotic fighter under the player's control
Arvoch Conflict, a shareware flight simulator by Star Wraith 3D Games
Asheron's Call, a fantasy massively multiplayer online role-playing genre
Assassin's Creed, a platformer/stealth video game
AssaultCube, a first-person shooter based upon the Cube engine
"AC" is an abbreviation for "Arcade game" game, and often used as a suffix to designate a new or separate version, or revision, of a game:
Melty Blood: Act Cadenza, a 2D fighting game featuring characters from Tsukihime
Guilty Gear XX Accent Core, a 2D fighting game, part of the Guilty Gear series
Tekken 5 on the PlayStation 2 features a mode that allows one to play the arcade versions of Tekken, Tekken 2, and Tekken 3, labeled "AC"

Music

AC/DC, a rock group
Adult contemporary music, a music genre also used to describe broadcast radio stations
Animal Collective, an experimental music group
Anal Cunt, a grindcore band
"AC", a song by Axium from Alive in Tulsa

Organizations

Action Congress
Ad Council
Ad Council Japan (AC Japan)
Akademikernes Centralorganisation, the Danish Confederation of Professional Associations
Alianza Costeña
Alternativa por el Cambio, a political party in Nicaragua
Anglican Communion
Appellate court
Astronomy club, common in schools and tertiary institutions
Alianţa Civică, the Romanian name for the Civic Alliance Foundation, an NGO
Ayala Corporation has the ticker symbol "AC" on the Philippine Stock Exchange
Asociación Civil, a title for non profit organizations in Spanish-speaking countries
AC Cars, British car manufacturer of the famous AC Cobra model

Schools

Aquinas College (disambiguation)
Atlantic College, one of the twelve United World Colleges
Assumption College, Worcester, Massachusetts, USA
Austin College, Sherman, Texas, USA

Miscellaneous

Abdominal Circumference
Advisory Circular (e.g. AC 20-115B), an acronym used by FAA
Anthrocon, the largest furry convention in the world held in Pittsburgh Philadelphia
Air conditioning (and air conditioner), the mechanical process of cooling air in enclosed spaces
Andrew Christian, an American fashion designer
Ante Christum, a Latin term meaning "before Christ"
Antichrist, in the Christian religion
Average cost, in economics
Another name for the Ansuz rune
Anarcho-capitalism a form of free-market anarchism
Associated Content

Translation

The word "AC" occurs as such in the following languages: English, Czech, Danish, German, Spanish, French, Korean, Italian, Latvian, Lithuanian, Dutch, Japanese, Norwegian (Bokmål), Norwegian (Nynorsk), Polish, Portuguese, Romanian, Russian, Slovak, Slovenian, Swedish, Thai, Turkish.

Translation(s) in other languages: Welsh: AC (gwahaniaethu), Esperanto: Ac, Hebrew: Ac, Ripuarian: AC (Watt ėßß datt?), Finnish: Ac, Vietnamese: Ac, Chinese: Ac.