To create a subclass of an abstract class in C++, you must provide an implementation for all of the pure virtual functions of the base class. Here's an example: 

By using the abstract term to describe classes with pure virtual functions in C++, you can clearly indicate to other developers that the class is not meant to be instantiated directly and must be subclassed to provide an implementation. 

In this code, the Shape class is an abstract class because it has a pure virtual function draw(). This means that the Shape class cannot be instantiated directly and must be subclassed to provide an implementation for the draw() function.