Singleton may refer to: Sciences, technology. Mathematics. Singleton (mathematics), a set with exactly one element. Singleton field, used in conformal field theory. Computing. Singleton pattern, a design pattern that allows only one instance of a class to exist. Singleton bound, used in coding theory. Singleton variable, a variable that is referenced only once. Singleton, a character encoded with one unit in variable-width encoding schemes for computer character sets. Singleton, an empty tag or self-closing tag in XHTML or XML coding. Social science.
https://en.wikipedia.org/wiki/Singleton