reflux

Etymology

It is borrowed from Medieval Latin refluxus (“a flowing back”),^{[2][3][4][5][6][7]} formed from re- (“back, again”) and fluxus (“a flowing”),^[2][4] from fluō (“to flow”),^[2][4][7] from Proto-Indo-European *bhleu-.^[4] The revised OED instead takes it as formed from English re- + flux, after the Medieval Latin word, which is recorded from the 12th century in British and continental sources;^[8][9] compare French reflux (1520), Italian riflusso and Spanish reflujo.^[8] The chemical sense probably follows French reflux, used in this sense by 1860.^[8] The verb is partly from the noun and partly formed from re- and the verb flux.^[8]

Earliest recorded meaning

A flowing back of the sea or a river, an ebb: about 1460, in John Lydgate's poems.^[8] Etymonline dates the word to the early 15th century.^[2]

Semantic evolution

The word was long used of the tide, often in the pairing flux and reflux, and figuratively of anything that ebbs and flows.^[2][8][9] Johnson (1755) defined it as the backward course of water, quoting Milton.^[10] In medicine it meant the backward flow of a bodily fluid from 1630, and especially the flow of stomach acid into the oesophagus, now often called acid reflux, from 1920;^[8] Etymonline dates the digestive sense to 1937.^[2] In chemistry the noun (1886) and the verb (1909) were used of boiling a liquid so that its vapour condenses and runs back into it, probably after French usage.^[8] Merriam-Webster dates the verb to 1926.^[3]

Timeline

• c. 1460 – a flowing back of the sea or a river, an ebb.^[8]
• 1630 – in medicine, a backward flow of a bodily fluid.^[8]
• 1632 – a flowing back in general, a return.^[8]
• 1652 – verb, to cause to flow back.^[8]
• 1662 – verb, to flow back.^[8]
• 1853 – reflux-valve.^[2]
• 1886 – in chemistry, the process of refluxing.^[8]
• 1909 – verb, to boil a liquid under a condenser so that the vapour returns to it.^[8]
• 1920 – the flow of stomach contents into the oesophagus.^[8] Etymonline dates this sense to 1937.^[2]

Meanings

Noun

1. A flowing back; an ebb, as in flux and reflux.^[3][7][8]
2. (medicine) A backward flow of a fluid in the body, especially of stomach contents into the oesophagus, causing heartburn.^[8][3]
3. (chemistry) The process of boiling a liquid in a vessel fitted with a condenser, so that the vapour condenses and runs back into the vessel.^[7][3][8]

Verb

1. (chemistry) To boil, or be boiled, under reflux.^[7][3][8]
2. To flow back; in medicine, of a fluid in the body, to flow backward through a valve or opening.^[8][3]

Word family

• gastroesophageal reflux

Related words

• flux
• fluent

References

1. ^ a b Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
3. ^ a b c d e f g Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
4. ^ a b c d The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
5. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
6. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
7. ^ a b c d e Collins English Dictionary (2023), Glasgow: HarperCollins
8. ^ a b c d e f g h i j k l m n o p q r s t u Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
9. ^ a b Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
10. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.