relation - an abstraction belonging to or characteristic of two entities or parts together

math, mathematics, maths - a science (or group of related sciences) dealing with the logic of quantity and shape and arrangement

function, mathematical function - a mathematical relation such that each element of one set is associated with at least one element of another set

parity - (mathematics) a relation between a pair of integers: if both integers are odd or both are even they have the same parity; if one is odd and the other is even they have different parity

transitivity - (logic and mathematics) a relation between three elements such that if it holds between the first and second and it also holds between the second and third it must necessarily hold between the first and third

reflexivity - (logic and mathematics) a relation such that it holds between an element and itself