the relation which one quantity or magnitude has to another of the same kind. it is expressed by the quotient of the division of the first by the second; thus, the ratio of 3 to 6 is expressed by / or /; of a to b by a/b; or (less commonly) the second term is made the dividend; as, a:b = b/a.-hence, fixed relation of number, quantity, or degree; rate; proportion; as, the ratio of representation in congress.