 To begin let’s distinguish between the “degree” or “adicity” or “arity” of relations (see, e.g., Armstrong 1978b: 75). Properties are “one-place” or “monadic” or “unary” because properties are only exhibited by particulars or other items, e.g., properties, individually or one by one. Relations are “many-place” or “\(n\)-adic” or “\(n\)-ary” (where \(n\gt 1)\) because they are exhibited by particulars only in relation to other particulars. A “2-place” or “dyadic” or “binary” relation is exhibited by one particular only in relation to another. A “3-place” or “triadic” or “ternary” relation is exhibited by one particular only in relation to exactly two others. And so on. Some examples. The relation that \(x\) stands to \(y\) whenever \(x\) is adjacent to \(y\) is binary. This is because it takes two things to be adjacent to one another. The relation that \(x\) stands to \(y\) and \(z\) whenever \(x\) is between \(y\) and \(z\) is ternary because it takes three things for one to fall between the other two.