bacterium

Etymology

It is borrowed from New Latin bactērium,^[2][3][4][1] from Ancient Greek βακτήριον (baktḗrion, “little staff”),^[2][5][1] a diminutive of βακτηρία (baktēría, “staff, cane”)^{[6][7][8][4][1]} or, according to the OED and Weekley, of βάκτρον (báktron, “stick, staff”).^[2][9] The American Heritage Dictionary refers it to the Indo-European root Proto-Indo-European *bak-,^[3] and Dictionary.com relates the Greek word to Latin baculum (“stick”) and bacillum.^[4] The name was given because the first bacteria discovered were rod-shaped.^[8][5][10] Etymonline treats it as the singular of bacteria.^[11]

Earliest recorded meaning

A microscopic single-celled organism: 1849–52, in Todd's Cyclopaedia of Anatomy and Physiology.^[2] Merriam-Webster Unabridged gives 1835 as its first known use,^[12] Etymonline about 1848,^[11] and Dictionary.com 1840–50.^[4]

Semantic evolution

Ayto says the word was coined in the 1840s and was at first sometimes anglicized as bactery, but the Latin form prevailed.^[10] Bacteria were once classed as fungi, and later usually as a distinct division of plants or an independent kingdom;^[7] Merriam-Webster Unabridged now defines them as a domain of prokaryotic microorganisms.^[12] The related bacillus, a diminutive of baculum, came later and was also named for the organism's rod shape.^[10][5] In sewage treatment the word was used from 1913 for a contact bed.^[2]

Timeline

• 1849 – a microscopic single-celled organism.^[2] Merriam-Webster Unabridged dates the word to 1835.^[12]
• 1913 – a contact bed in sewage treatment.^[2]

Meanings

Noun

1. Any of a large group of single-celled prokaryotic microorganisms, round, rod-shaped or spiral, living in soil, water and the bodies of plants and animals; many are symbiotic and some cause disease: A single bacterium can divide every twenty minutes.^[12][7][2]

Word family

• archaebacterium
• bacterial
• bactericidal
• bactericide
• bacteriology
• bacteroid
• cyanobacterium
• enterobacterium

Related words

• bacteria
• bacillus
• baguette

Usage notes

Bacterium is the singular and bacteria the plural, as in Latin; the use of bacteria as a singular is usually considered nonstandard.^[1][13]

References

1. ^ a b c d e Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e f g h Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
3. ^ a b The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
4. ^ a b c d Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
5. ^ a b c Cresswell, Julia (2021), Oxford Dictionary of Word Origins, 3rd ed., Oxford: Oxford University Press
6. ^ Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
7. ^ a b c Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
8. ^ a b Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
9. ^ Weekley, Ernest (1921), An Etymological Dictionary of Modern English, London: John Murray
10. ^ a b c Ayto, John (2005), Word Origins: The Secret Histories of English Words from A to Z, 2nd ed., London: A & C Black
11. ^ a b Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
12. ^ a b c d Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
13. ^ Collins English Dictionary (2023), Glasgow: HarperCollins