ra·tio (rāshō, rāshē-ō′)
n. pl. ra·tios
1. Relation in degree or number between two similar things.
2. The relative value of silver and gold in a currency system that is bimetallic.
3. Mathematics A relationship between two quantities, normally expressed as the quotient of one divided by the other; for example, the ratio of 7 to 4 can be written 7:4 or 7/4. A ratio can often also be expressed as a decimal or percentage.
[Latin ratiō, calculation, from ratus, past participle of rērī, to reckon, consider; see ar- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.