The act of casting a reference of a base class to one of its derived classes; a type cast which breaks the abstraction model; the abstraction may have to be refactored or eliminated
Also known as type refinement
1 identifiers linking downcasting across the web's reference databases
From Wikipedia, the free encyclopedia · Read full article · Text CC BY-SA 4.0
In class-based programming, downcasting, or type refinement, is the act of casting a base or parent class reference, to a more restricted derived class reference. This is only allowable if the object is already an instance of the derived class, and so this conversion is inherently fallible. In contrast upcasting, explicitly treating an object as if it's an instance of one of its superclasses, is always possible.