A software framework is a reusable design for a software system (or subsystem). This is expressed as a set of abstract classes and the way their instances collaborate for a specific type of software. Software frameworks can be object-oriented designs. Although designs don't have to be implemented in an object-oriented language, they usually are and in some ways they can be considered the object-oriented equivalent of software libraries. A software framework may include support programs, code libraries, a scripting language, or other software to help develop and glue together the different components of a software project. Various parts of the framework may be exposed through an application programming interface (API).
From : http://en.wikipedia.org/wiki/Software_framework