If a relation is a subset of the Cartesian product of two sets, is there a special term for an individual element of a relation? Might that term be "relationship"?
You might, I suppose, say that the pair $\langle 1, 2\rangle$ is an instance of the 'less than' relation, if you want to say close to informal talk about relations.
(Mind you, call me pernickety, but I'd rather you didn't say the relation is a set of ordered pairs -- the set is the extension of the relation. But that's a sermon for another occasion!)