n. A relation of parallelism, or similarity in position and relation. See correspondent, a., 1, and correspond, 1.n. A relation of conformableness or congruity; the state of being adapted or reciprocally related in form or character; a condition of agreement or relative fitness.n. In mathematics, a mode of relation by which each individual of one set is related to a definite number of individuals of another (or the same) set, and a definite number of individuals of the first set is related to each individual of the second set. If M is the first number and N the second, the relation is said to be an N to M correspondence.n. That which corresponds to something else; one of a pair or series that is complementary to another or others.n. Intercourse between persons at a distance by means of letters sent and answers received.n. Hence The letters which pass between correspondents: as, the correspondence of Goethe and Schiller is published.n. Friendly intercourse; reciprocal exchange of offices or civilities; social relation.