What is meant by the Polymorphism definition?


Based on many tutorials that I have read, the following is the definition of Polymorphism:

Polymorphism is the ability of an object to take on many forms.

Now let’s assume that we have an Animal parent class, and a Dog and a Cat child classes.

Is the above Polymorphism definition means that an Animal variable can have many forms in the sense that an Animal variable can be an Animal or it can be a Dog or it can be a Cat, or does it mean something else?