Definitions

1. noun

A person or thing that is single or solitary.

“The new mother was a singleton, having only one child.”

2. noun

In object-oriented programming, a class that can have only one object (an instance of the class).

“The programmer used a singleton to ensure that only one instance of the database was created.”

3. noun

A horse or other animal that is the only offspring of its parents.

“The breeder sold the singleton foal for a high price.”

4. adjective

Single, solitary, or isolated.

“The singleton tree stood out in the vast desert landscape.”