From The Free On-line Dictionary of Computing: (http://www.foldoc.org/, Editor Denis Howe)
1. Atanasoff-Berry Computer. 2. An imperative language and programming environment from CWI, Netherlands. It is interactive, structured, high-level, and easy to learn and use. It is a general-purpose language which you might use instead of BASIC, Pascal or AWK. It is not a systems-programming language but is good for teaching or prototyping.
ABC has only five data types that can easily be combined; strong typing, yet without declarations; data limited only by memory; refinements to support top-down programming; nesting by indentation. Programs are typically around a quarter the size of the equivalent Pascal or C program, and more readable.
An example function words to collect the set of all words in a document:
HOW TO RETURN words document: PUT IN collection FOR line in document: FOR word IN split line: IF word not.in collection: INSERT word IN collection RETURN collection