The-one-and-the-only is used to define a class which has only one instance. It refers to an instance of an concept that defines the concept and is the only instance of the concept.


The example shows how to use the keyword.

Example: The first sentence is equivalent to the combination of the second and the third sentence.
The-one-and-only singlethon is a cat.
The singlethon is a cat.
Every singlethon is the singlethon.