I've always wondered where the word polymorphism word came from. I know what polymorphism is and I use it of course, but I just don't understand why this technique is called polymorphism.
Note that I'm not a native English speaker, and I will thank you if you'll use simple English in your answers.
It comes from the greek roots "poly" (many) and "morphe" (form). A polymorphic object can take on many forms (it can be represented by a pointer to any of its ancestor classes). A polymorphic function can also take on many forms (it can be made to operate on objects that are actually of different types).
Polymorphism is an English word that predates its use in computer science. It means "the ability to assume different forms or shapes." (reference http://en.wiktionary.org/wiki/polymorphism#Etymology)
This is analogous to the computer science concept in which an object can be treated as having many different types.
The word of Polymorphism comes from ancient greek. Something is polymorph, if it has more than one "shape/form".