From The Free On-line Dictionary of Computing: (http://www.foldoc.org/, Editor Denis Howe)
A high-level programming language designed by Niklaus Wirth at ETH in 1978. It is a derivative of Pascal with well-defined interfaces between modules, and facilities for parallel computation. Modula-2 was developed as the system language for the Lilithworkstation.
The central concept is the module which may be used to encapsulate a set of related subprograms and data structures, and restrict their visibility from other portions of the program. Each module has a definition part giving the interface, and an implementation part.