spi·​ro·​chete ˈspī-rə-ˌkēt How to pronounce spirochete (audio)
variants or less commonly spirochaete
: any of an order (Spirochaetales) of slender spirally undulating bacteria including those causing syphilis and Lyme disease

Example Sentences

Recent Examples on the Web To this day, the mechanism of action of this malaria-on-syphilis, parasite-on-spirochete action is unknown (7). Rebecca Kreston, Discover Magazine, 31 May 2014 The spirochete lives permanently as a symbiont in the patient. Dick Teresi, Discover Magazine, 17 June 2011 The factor that determines whether acute Lyme disease becomes chronic is the interval between inoculation of the Lyme spirochete and the commencement of adequate treatment. BostonGlobe.com, 3 June 2022 Multiple sclerosis is often associated with the commonplace Epstein-Barr virus, rheumatic fever with the same bacteria that cause strep throat, and Lyme, famously, with bites from ticks that carry a spirochete called Borrelia burgdorferi. Ross Douthat, Star Tribune, 2 Feb. 2021 Through this method, India became yaws-free in 2016, though the emergence of antibiotic resistance in the spirochete may complicate efforts. Quanta Magazine, 3 Dec. 2019 Acute encephalitis syndrome, including Japanese encephalitis, is caused by several different viruses, bacteria, fungi, parasites, spirochetes, chemical and toxins. Washington Post, 2 Nov. 2019 Barbour had spent the year learning the complex requirements for growing Borrelia, a type of spirochete transmitted by ticks or lice. Allen Steere, BostonGlobe.com, 22 Aug. 2019 In 1982, while dissecting the mid-gut of a tiny nymphal Ixodes scapularis tick, Burgdorfer noted what looked like spirochetes. Allen Steere, BostonGlobe.com, 22 Aug. 2019 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'spirochete.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Word History


borrowed from New Latin Spirochaeta, bacterial genus, from Latin spīra "coil, twist, whorl" + Greek -o- -o- + chaítē "growth of hair, flowing locks" — more at spire entry 3, chaeta

Note: The genus was introduced by the German zoologist Christian Gottfried Ehrenberg (1795-1876) in "Dritter Beitrag zur Erkenntnis grosser Organisation in der Richtung des kleinsten Raumes," Physikalische Abhandlungen der Königlichen Akademie der Wissenschaften zu Berlin: aus dem Jahre 1833 (Berlin, 1835), p. 313. Ehrenberg had found the organism, which he named Spirochaeta plicatilis (Latin plicātilis "capable of being folded"), in water left from the previous winter ("im überwinterten Wasser") in Berlin on April 2, 1832.

First Known Use

circa 1877, in the meaning defined above

Time Traveler
The first known use of spirochete was circa 1877

Dictionary Entries Near spirochete

Cite this Entry

“Spirochete.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/spirochete. Accessed 29 Mar. 2023.

Kids Definition


variants also spirochaete
: any of a group of slender coiled bacteria including one that causes syphilis

Medical Definition


variants or chiefly British spirochaete
: any bacterium of the order Spirochaetales including those causing syphilis and relapsing fever

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