Definition:Commutative/Elements

Definition
Let $\circ$ be a binary operation.

Two elements $x, y$ are said to commute :
 * $x \circ y = y \circ x$

Thus $x$ and $y$ can be described as commutative under $\circ$.

Also known as
The terms permute and permutable can sometimes be seen instead of commute and commutative.