\begin{definition}[Definition:Opposite Ring]
Let $\struct {R, +, \times}$ be a ring.
Let $* : R \times R \to R$ be the binary operation on $S$ defined by:
:$\forall x, y \in S: x * y = y \times x$
The '''opposite ring''' of $R$ is the algebraic structure $\struct {R, +, *}$.
\end{definition}