Object-Orientation FAQ

The use of derived classes and virtual functions is often called "object-
oriented programming".  Furthermore, the ability to call a variety of
functions using exactly the same interface - as is provided by virtual
functions - is sometimes called "polymorphism".

[The Author notes this is a functional view of polymorphism (as provided in
C++).  [Stroustrup 91, p. 136] has an example of polymorphism with void *'s,
but a newer template function is incomparably preferable, as implied in
[Stroustrup 90, ch 14]]

Rumbaugh's Definition [Rumbaugh 91, p. 2]:

"Polymorphism" means that the same operation may behave differently on
different classes.