Is it possible to declare an abstract method outside the definition of an abstract class?

In C#, an abstract method can only be declared within an abstract class. This is because an abstract method has no implementation, and the class containing such a method must be declared as abstract.

Attempting to declare an abstract method outside of an abstract class will result in a compiler error.

Example of a correct declaration:

abstract class BaseClass
{
    public abstract void AbstractMethod();
}

Example of an incorrect declaration (will produce an error):

class ConcreteClass
{
    public abstract void AbstractMethod(); // Error
}