ration.[L., fr. reri, ratus, to reckon, believe, think, judge. See Reason.]1. (Math.) 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 3/6 or 1/2; of a to b by a/b; or (less commonly) the second term is made the dividend; as, a:b = b/a.()()2. Hence, fixed relation of number, quantity, or degree; rate; proportion; as, the ratio of representation in Congress.()Compound ratio, Duplicate ratio, Inverse ratio, etc. See under Compound, Duplicate, etc. -- Ratio of a geometrical progression, the constant quantity by which each term is multiplied to produce the succeeding one.()