Definition:Kleene Closure

Definition
Let $S$ be a set.

The Kleene closure of $S$, denoted $S^*$, is the set of all ordered tuples in $S$.

Also defined as
Sometimes the Kleene closure is considered to be an algebraic structure, endowed with the concatenation operation $*$.

Also known as
The Kleene closure is also called the Kleene star, reminiscent of its notation.

Also see

 * Defintion:Free Monoid on Set