Singleton variable

In computer programming a singleton variable is a variable that is referred to only once.
Examples of where a variable might only be referenced once is as a dummy argument in a function call, or when its address is assigned to another variable which subsequently accesses its allocated storage.
Singleton variables sometimes occur because a mistake has been made – such as assigning a value to a variable and forgetting to use it later, or mistyping one instance of the variable name. Some compilers and lint-like tools flag occurrences of singleton variables.