iodine

Etymology

The English chemist Sir Humphry Davy named it in 1814;^[2][3][4][5] it is borrowed from French iode (“iodine”) with the chemical suffix -ine, to match chlorine and fluorine.^[2][3][4][6] The French name was given in 1812 by the chemist Joseph Louis Gay-Lussac,^[3][4][5][2] although Klein credits it to Bernard Courtois, who discovered the element in 1811.^[6][4] It is from Ancient Greek ἰώδης (iṓdēs, “violet-coloured”)^{[2][5][7][8][9]} or ἰοειδής (ioeidḗs),^{[3][4][10][11][1]} from ἴον (íon, “violet”) and -ειδής (-eidḗs, “like”), from εἶδος (eîdos, “appearance, form”),^[2][3][4][6] after the violet colour of the vapour the crystals give off when heated.^[3][4][2] Collins and Dictionary.com, however, take the Greek adjective as originally meaning "rust-coloured", reinterpreted as "violet-like" through a mistaken connection with íon.^[12][13] Greek íon, which originally began with a w-, is related to Latin viola, the source of violet;^{[4][14][10][15]} Barnhart and Partridge consider both to be from a non-Indo-European Mediterranean language.^[4][14]

Earliest recorded meaning

The chemical element: 1814, in Davy's paper in the Philosophical Transactions of the Royal Society.^[2][4][3]

Semantic evolution

The word has kept its chemical sense, and was soon used for the element's preparations as well: from 1843 there was a verb iodine, to treat with iodine or iodize,^[2][7] and iodine also names the antiseptic solution, tincture of iodine.^[1] Davy's name was the model for later derivatives such as iodoform, formed after chloroform.^[9][5] In southern Lincolnshire dialect, iodine was a name for the greater celandine.^[16]

Timeline

• 1812 – French iode named by Gay-Lussac.^[3][4][5]
• 1814 – the element, named by Davy.^[2][3][4]
• 1843 – verb, to treat with iodine.^[2]

Meanings

Noun

1. A nonmetallic chemical element of the halogen group, symbol I, atomic number 53, forming blackish crystals that give off a violet vapour; it is needed by the thyroid and used in medicine, photography and dyes.^{[12][11][2][7]}
2. A solution of iodine used as an antiseptic: The nurse dabbed iodine on the graze.^[1]

Verb

1. (rare) To treat with iodine; to iodize.^[2][7]

Word family

• povidone-iodine
• iodimetry
• iodinate
• radioiodine
• quartz-iodine lamp

Related words

• iodate
• iodic
• iodide
• iodous
• violet
• iodoform
• iodize
• chlorine
• fluorine
• -oid

References

1. ^ a b c d Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h i j k l Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e f g h i Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b c d e f g h i j k l Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
5. ^ a b c d e Weekley, Ernest (1921), An Etymological Dictionary of Modern English, London: John Murray
6. ^ a b c Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
7. ^ a b c d Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
8. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
9. ^ a b Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
10. ^ a b The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
11. ^ a b Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
12. ^ a b Collins English Dictionary (2023), Glasgow: HarperCollins
13. ^ Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
14. ^ a b Partridge, Eric (1966), Origins: A Short Etymological Dictionary of Modern English, 4th ed., London: Routledge & Kegan Paul
15. ^ Ayto, John (2005), Word Origins: The Secret Histories of English Words from A to Z, 2nd ed., London: A & C Black
16. ^ Wright, Joseph, ed. (1898–1905), The English Dialect Dictionary, 6 vols., Oxford: Henry Frowde; via EDD Online 4.0, University of Innsbruck (CC BY 4.0)