CONGRUOUS, that which corresponds to or agrees with anything (Lat. congruere, to agree); the derivation appears in "congruence," a condition of such correspondence or agreement, a term used particularly in mathematics, e.g., for a doubly infinite system of lines (see SURFACE), and in the theory of numbers, for the relation of two numbers, which, on being divided by a third number, known as the modulus, leave the same remainder. (See