lactic

Etymology

It is borrowed from French lactique,^[2][3][4] formed from Latin lactis, genitive of lac (“milk”), and -ique.^[2][3] The Oxford dictionaries and Collins instead take it directly from the stem lact- with the English suffix -ic.^[5][6][7][8] Etymonline reconstructs the Latin noun as from Proto-Indo-European *g(a)lag- (“milk”).^[3] The same Latin noun is the source of lettuce, through lactūca,^[9][10] and Klein compares galactic.^[11]

Earliest recorded meaning

Of or relating to milk, in the chemical name lactic acid, the acid formed in sour milk: 1789, in R. Kerr's translation of Lavoisier's Elements of Chemistry.^[5] Barnhart, Etymonline and Merriam-Webster Unabridged date the word to 1790.^[2][3][4]

Semantic evolution

The word is chiefly a term of chemistry and biochemistry,^[6] and lactic acid got its name because it was obtained from sour milk.^[3] The souring of milk by bacteria was called lactic fermentation,^[5] and Merriam-Webster Unabridged records a sense "involving the production of lactic acid".^[4] From 1910, first in an advertisement in Health & Strength, it has also described dairy products, wine and the like with an unusually high proportion of lactic acid through inoculation with lactobacilli, and the bacteria that produce it.^[5] The Shorter Oxford notes that lactic acid forms in the body, especially as the end product of glycolysis.^[6]

Timeline

• 1789 – of milk, as in lactic acid, the acid in sour milk.^[5] Barnhart and Etymonline date it to 1790.^[2][3]
• 1910 – of dairy products, wine and the like: unusually high in lactic acid; of bacteria: producing it.^[5]

Meanings

Adjective

1. Of, relating to or obtained from milk.^{[8][12][7][4]}
2. Obtained from sour milk or whey, as lactic acid is.^[4][5]
3. Involving the production of lactic acid: lactic fermentation.^[4][5]
4. Of dairy products, wine and the like: containing an unusually high proportion of lactic acid, through inoculation with lactobacilli; of bacteria: producing lactic acid.^[5]

Word family

• lactic acid

Related words

• lactate
• lactation
• lettuce
• lactose
• lacteal
• galactic

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
3. ^ a b c d e f Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b c d e f Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
5. ^ a b c d e f g h i Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
6. ^ a b c Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
7. ^ a b Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
8. ^ a b Collins English Dictionary (2023), Glasgow: HarperCollins
9. ^ Ayto, John (2005), Word Origins: The Secret Histories of English Words from A to Z, 2nd ed., London: A & C Black
10. ^ Cresswell, Julia (2021), Oxford Dictionary of Word Origins, 3rd ed., Oxford: Oxford University Press
11. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
12. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt