Rondo: loosely means 'return': its a form of classical music (which has been introduced into modern genres as well) which has a theme that keeps returning between new themes. It can be represented like this:
A B A C A B A
A B A C A D A B A C A
as long as the main theme returns.
An example would be Mozart's 'Rondo All Turca' but since I didn't write it or publish it I shant give an audio example of it.