ratio

Pronunciation

• IPA: UK /ˈreɪ.ʃi.əʊ/, US /ˈreɪ.ʃi.oʊ/, /ˈreɪ.ʃoʊ/^[1]

Etymology

It is borrowed from Latin ratiō (“reckoning, calculation; reason”),^[2][3][4] from ratus, the past participle of rērī (“to reckon, think”),^[2][5][3] from the PIE root Proto-Indo-European *re- (“to think, reason, count”).^[2] It is a doublet of ration and reason.^[3]

Earliest recorded meaning

Reason or rationale, in theological writing: 1636 in the OED, the 1630s in Etymonline,^[6][2] while MWU dates the first sense to 1638.^[6][2][7]

Semantic evolution

The mathematical sense, the relation between two magnitudes of the same kind, is from 1660.^[6][3] Looser comparisons between things that can't be precisely measured are from 1808, and the value of silver against gold in a currency with both from 1879.^[6] In the 18th century ratio was also briefly used for a ration.^[6][4] In philosophy and law the old sense survives in Latin phrases such as ratio decidendi, the reason for a court's decision.^[6][8] Etymonline notes that Latin ratio often translated Greek logos in philosophy, though it lacked the Greek sense “word, speech”.^[2]

Timeline

• 1636 – reason, rationale.^[6]
• 1660 – the mathematical sense.^[6][3]
• 1760 – a ration (obsolete).^[6]
• 1879 – the ratio of gold to silver.^[6]
• 1943 – the verb, to enlarge or reduce in proportion.^[6]

Modern meaning

Noun

1. The relation in size or number between two things, often written as a quotient or proportion.
2. The relative value of gold and silver in a currency system using both.

Word family

• ratiometer
• loss ratio
• anharmonic ratio
• aspect ratio
• compression ratio
• cross ratio
• current ratio
• gear ratio

Related words

• rational
• irrational
• ration
• reason
• ratify
• rate

References

1. ^ Jones, Daniel (2011), Cambridge English Pronouncing Dictionary, 18th ed., ed. Peter Roach, Jane Setter and John Esling, Cambridge: Cambridge University Press
2. ^ a b c d e f Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
3. ^ a b c d e Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
4. ^ a b Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
5. ^ The American Heritage Dictionary of the English Language (2000), 4th ed., Boston: Houghton Mifflin
6. ^ a b c d e f g h i j k Simpson, J. A.; Weiner, E. S. C., eds. (1989), The Oxford English Dictionary, 2nd ed., Oxford: Clarendon Press
7. ^ Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
8. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press