chlorine

Etymology

It was coined in 1810 by the English chemist Sir Humphry Davy,^[2][3][4][5] formed from English chloro- + -ine from Ancient Greek χλωρός (khlōrós, “pale green, greenish yellow”),^[2][4][6][7] with allusion to the colour of the gas.^[2][3][4] Etymonline derives the Greek adjective from Proto-Indo-European *ghel- (“to shine”), whose derivatives denote green and yellow.^[3] The OED compares German Chlorine (1811 or earlier), and the later French chlore and Chlor (both 1814).^[2] Klein compares bromine, fluorine and iodine.^[6]

Earliest recorded meaning

The chemical element, a yellowish-green pungent gas: 1810, in Davy's paper read to the Royal Society on 15 November.^[2][4]

Semantic evolution

The gas had been discovered by the Swedish chemist Carl Scheele in 1774 and was called oxymuriatic acid gas;^[4][3] Davy first identified it as an element and named it after its colour.^[4][5] Etymonline adds the older name dephlogisticated marine acid.^[3] From 1832 the word was also used of a chlorine compound, such as a bleach or disinfectant, and since 1864 of an atom or ion of chlorine.^[2] Ayto notes that chloroform, originally French, is a secondary formation based on the name of the element, while chlorophyll was named directly for its green colour.^[5]

Timeline

• 1774 – the gas is discovered by Scheele, as oxymuriatic acid gas.^[4][3]
• 1810 – named chlorine by Davy.^[2][3][4]
• 1832 – a chlorine compound; a bleach or disinfectant.^[2]
• 1864 – an atom or ion of chlorine.^[2]

Meanings

Noun

1. A toxic, pungent, greenish-yellow gas, a chemical element of the halogen group (atomic number 17, symbol Cl), used in water treatment, as a bleach and disinfectant, and in making many chemicals.^[8][9][2]
2. A chlorine compound used as a bleach or disinfectant: The pool smelled strongly of chlorine.^[2]

Word family

• chlorinous
• antichlor
• chloro-
• chloral
• chloric
• chloride
• chlorinate

Related words

• chlorate
• chlorophyll
• chloroform
• bromine
• fluorine
• iodine

Usage notes

A rare adjective chlorine, light green or grass-green, is recorded from before 1849, in Poe.^[2][9][10]

References

1. ^ 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 Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
4. ^ a b c d e f g h Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
5. ^ a b c Ayto, John (2005), Word Origins: The Secret Histories of English Words from A to Z, 2nd ed., London: A & C Black
6. ^ a b Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
7. ^ Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
8. ^ Collins English Dictionary (2023), Glasgow: HarperCollins
9. ^ a b Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
10. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press