ratio

UK: /ˈreɪʃiəʊ/ US: /ˈreɪʃoʊ, -ʃiˌoʊ/ ,(rā′shō, -shē ō′)

Inflections of 'ratio' (n): npl: ratios

WordReference Random House Learner's Dictionary of American English © 2025

ra•tio /ˈreɪʃoʊ, -ʃiˌoʊ/   n. [countable] , pl. -tios. 

1. Mathematics the relation between two numbers or amounts, with respect to the number of times the first contains the second:
   The ratio of 3 to 9 is the same as the ratio of 1 to 3.
2. Mathematics rate;
   proportion:
   The ratio of acceptances to rejections is very high.

See -ratio-.
-ratio-, root. 

1. -ratio- comes from Latin, where it has the meaning "logic;
   reason;
   judgment.'' This meaning is found in such words as: irrational, overrated, rate, ratify, ratio, ration, rational.

WordReference Random House Unabridged Dictionary of American English © 2025

ra•tio  (rā′shō, -shē ō′), n., pl. -tios. 

1. Mathematics the relation between two similar magnitudes with respect to the number of times the first contains the second:
   the ratio of 5 to 2, written 5:2 or 5/2.
2. Mathematics proportional relation;
   rate:
   the ratio between acceptances and rejections.
3. [Finance.] the relative value of gold and silver in a bimetallic currency system.

• Latin ratiō a reckoning, account, calculation, derivative (see -tion) of the base of rērī to judge, think
• 1630–40

Collins Concise English Dictionary © HarperCollins Publishers::

ratio / ˈreɪʃɪˌəʊ/ noun ( -tios)

1. a measure of the relative size of two classes expressible as a proportion: the ratio of boys to girls is 2 to 1
2. a quotient of two numbers or quantities
   See also proportion6

Etymology: 17th Century: from Latin: a reckoning, from rērī to think; see reason