What is the meaning of Subclass?

A secondary class within a main class.

A rank directly below class.

An object class derived from another class (its superclass) from which it inherits a base set of properties and methods.

(in object-oriented programming) To create a subclass of (some class).

To cause (an object) to act as an instance of a subclass (by creating the desired subclass and instantiating an object of this subclass).

Source: wiktionary.org