ratio Meaning, Definition & Usage

  1. noun the relative magnitudes of two quantities (usually expressed as a quotient)
  2. noun the relation between things (or parts of things) with respect to their comparative quantity, magnitude, or degree
    • an inordinate proportion of the book is given over to quotations
    • a dry martini has a large proportion of gin


Ra"ti*o noun
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 &frac36; or ½; of a to b by ab; or (less commonly) the second is made the dividend; as, a:b = ba. ✍ Some writers consider ratio as the quotient itself, making ratio equivalent to a number. The term ratio is also sometimes applied to the difference of two quantities as well as to their quotient, in which case the former is called arithmetical ratio, the latter, geometrical ratio. The name ratio is sometimes given to the rule of three in arithmetic. See under Rule.
  2. Hence, fixed relation of number, quantity, or degree; rate; proportion; as, the ratio of representation in Congress.

Webster 1913