path·​o·​gen | \ ˈpa-thə-jən How to pronounce pathogen (audio) \

Definition of pathogen

: a specific causative agent (such as a bacterium or virus) of disease

Examples of pathogen in a Sentence

Recent Examples on the Web The three variants now circulating in Europe are believed to be more easily transmitted, and potentially more dangerous, than the original pathogen that still makes up the majority of cases in Europe. Nick Kostov, WSJ, "Covid-19 Variants Outpace Europe’s Slow Vaccine Rollout," 16 Feb. 2021 Studies have shown that the body's virus-fighting cells are able to remember the pathogen from a previous illness and attack, either killing the infection or staving off more severe symptoms. Meryl Kornfield,, "First known patient reinfected with South Africa coronavirus variant is in critical condition," 14 Feb. 2021 This comparatively moisture-free air provides a clear path for dispersal of airborne particles of viruses such as SARS-CoV2, the pathogen that causes COVID-19. Akiko Iwasaki, Scientific American, "Another Way to Protect Against COVID Beyond Masking and Social Distancing," 19 Jan. 2021 Researchers used two major sources of data in their work, tracking human Lyme disease incidents as reported to the CDC as well as scientific studies conducted in the Midwest that looked for the ticks that transmit the Lyme pathogen. Scot Bertram, Washington Examiner, "New model from University of Illinois could help limit spread of Lyme disease," 18 Jan. 2021 After a second contact with the enemy, more memory cells are made, which means the next time the pathogen is seen, that swift response will be bigger. Popular Science, "Is one dose of the COVID-19 vaccine enough?," 12 Jan. 2021 As such, a spike in deaths does not, in and of itself, say all that much about how a pathogen such as the novel coronavirus is spreading in a community. Paul Sisson, San Diego Union-Tribune, "San Diego County ends 2020 with largest single-day COVID-19 death total of the year," 31 Dec. 2020 In many traditional vaccines, this is done by putting a weakened or inactivated pathogen into the body. Annie Berman, Anchorage Daily News, "Alaska coronavirus Q&A: Your vaccine questions, answered," 21 Dec. 2020 Older vaccines work by injecting dead or weakened virus to teach the immune system to recognize the real pathogen. Democrat-gazette Staff From Wire Reports, Arkansas Online, "FDA's advisers vote to endorse second vaccine," 18 Dec. 2020

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

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First Known Use of pathogen

1880, in the meaning defined above

History and Etymology for pathogen

patho- + -gen, after pathogenic, pathogenesis

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Time Traveler for pathogen

Time Traveler

The first known use of pathogen was in 1880

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Statistics for pathogen

Last Updated

22 Feb 2021

Cite this Entry

“Pathogen.” Dictionary, Merriam-Webster, Accessed 27 Feb. 2021.

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More Definitions for pathogen



English Language Learners Definition of pathogen

medical : something (such as a type of bacteria or a virus) that causes disease


patho·​gen | \ ˈpath-ə-jən How to pronounce pathogen (audio) \

Medical Definition of pathogen

: a specific causative agent (as a bacterium or virus) of disease

More from Merriam-Webster on pathogen

Britannica English: Translation of pathogen for Arabic Speakers Encyclopedia article about pathogen

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