title: Is "polymorphic base class" a part of C++ standard?
body: <p>For a bass class that has a virtual function usually call "a polymorphic base class". In this case <code>Car</code> class</p>
  
  <pre><code>class Car
  {
   virtual void drive(){std::cout &lt;&lt; "drive right";}
  };
  
  class EuropeCar: public Car
  {
   void drive(){std::cout &lt;&lt; "drive left";}
  }
  </code></pre>
  
  <p>Is <code>polymorphic base class</code> a general slang such as <code>pure abstract class</code> or a part of C++ standard?</p>