From Citizendium, the Citizens' Compendium
- Abc (alphabet) : A sorted list of character symbols in languages repesented with Roman characters
- Abc (music notation) : A programming language, created by Chris Walshaw, for creating sheet music, which uses the ASCII character set as input.
- Army Battle Command System : The set of information systems and components that support the operational-level command and control of the U.S. Army, abbreviated ABCS
- American Broadcasting Company : Add brief definition or description