finitary relation

A finitary relation over a sequence of sets $X_1,\dots ,X_n$ is a subset of the Cartesian product $X_1\times \dots \times X_n$, i.e. a set of $n$-tuples $(x_1,\dots ,x_n)$ with each $x_i\in X_i$ such that the elements of each tuple are related.

The most common is a binary relation.