penicillin

Etymology

It is formed from English penicillium + -in,^{[2][3][4][5][6][7]} and was coined by the British bacteriologist Alexander Fleming,^[8][9][10] who discovered the substance in 1928.^[10] The genus name of the mould, New Latin Penicillium, was given by H. F. Link in 1809, from Latin pēnicillus (“painter's brush”) and the suffix -ium;^[2] the moulds were so named because their spore-bearing cells look like small brushes.^[10][7][8] The Latin word, also the source of pencil, is a diminutive of pēniculus (“brush”), itself a diminutive of pēnis (“tail”).^[8][11] Ayto gives the Latin word in the neuter form pēnicillum.^[11]

Earliest recorded meaning

A substance with antibiotic action obtained from cultures of the mould Penicillium notatum: 1929, in Fleming's paper in the British Journal of Experimental Pathology, where he explains the name.^[2]

Semantic evolution

At first penicillin meant the crude antibacterial substance that Fleming found in mould cultures;^[2][3] once its chemistry was known, the word came to cover a whole group of related natural and semi-synthetic antibiotics, distinguished by letters, as in penicillin G.^[2][3] In the mid-20th century penicillin A and penicillin B were also names for another mould product, notatin, a use that did not last.^[3] Derivatives such as penicillinase, an enzyme of bacteria that destroys penicillins, date from the mid-20th century.^[3]

Timeline

• 1929 – an antibiotic substance obtained from the mould Penicillium notatum.^[2][6][10]

Meanings

Noun

1. Any of a group of antibiotics produced by moulds of the genus Penicillium or made synthetically, used against many bacterial infections such as pneumonia.^{[12][6][3][2]}
2. (chemistry) Any of the related acids with a common ring structure from which these drugs are formed.^[6][3]

Word family

• ampicillin
• penicillamine
• penicillinase

Related words

• penicillium
• pencil
• penis

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b c d e f g Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
4. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
5. ^ The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
6. ^ a b c d Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
7. ^ a b Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
8. ^ a b c Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
9. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
10. ^ a b c d Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
11. ^ a b Ayto, John (2005), Word Origins: The Secret Histories of English Words from A to Z, 2nd ed., London: A & C Black
12. ^ Collins English Dictionary (2023), Glasgow: HarperCollins