Definition:Comparable Elements

Definition
Let $\struct {S, \RR}$ be a relational structure.

Two elements $x, y \in S, x \ne y$ are comparable if either $x \mathrel \RR y$ or $y \mathrel \RR x$.

Also defined as
While the concept of comparable elements is defined as here for a general relational structure, it is common for expositions to discuss them in the context of orderings only.

Also see
If $x$ and $y$ are not comparable then they are non-comparable.