path·​o·​gen | \ˈpa-thə-jən \

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

Ticks that transmit Lyme disease can also transmit other pathogens causing less-common diseases such as anaplasmosis and babesiosis. Sumathi Reddy, WSJ, "New Effort for Lyme Disease Vaccine Draws Early Fire," 9 July 2018 To check, the team examined the pathogen-recognition genes in 32 sedentary and migratory species. Asher Elbein, New York Times, "Some Birds Are Better Off With Weak Immune Systems," 25 June 2018 The pathogen overwinters on infected tubers and in plant debris. The Editors Of Organic Life, Good Housekeeping, "Grow Healthy Food By Identifying + Treating These Common Plant Diseases," 21 July 2015 The submissions showed a variety of species of tick, including some that carry pathogens for Lyme disease, which the CDC reports 300,000 cases of a year. NBC News, "'Citizen scientists' take on growing threat of tick-borne diseases," 12 July 2018 Robbins writes that anthroponeses, or diseases passed from humans to animals, are one concern: Orcas are consistently exposed to airborne pathogens that their immune systems may not equipped to fend off. Meilan Solly, Smithsonian, "Pacific Northwest Orca Population Hits 30-Year-Low," 10 July 2018 Searching for ancient diseases Answering some of those remaining questions will require more ancient viral genomes, not just from hepatitis B but from other pathogens. Kiona N. Smith, Ars Technica, "Genghis Khan’s Mongol horde probably had rampant Hepatitis B," 11 May 2018 One possibility is that alpha-synuclein produced in the gastrointestinal nervous system helps fight off pathogens. Diana Kwon, Scientific American, "Does Parkinson’s Begin in the Gut?," 8 May 2018 Scientists from Pursdue University engineered a silk that can kill pathogens when activated by a light. Laura Yan, Popular Mechanics, "Meet the Surprising Medical Material of the Future: Silk," 5 May 2018

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.

See More

First Known Use of pathogen

1880, in the meaning defined above

History and Etymology for pathogen

International Scientific Vocabulary

Keep scrolling for more

Learn More about pathogen

Statistics for pathogen

Last Updated

7 Nov 2018

Look-up Popularity

Time Traveler for pathogen

The first known use of pathogen was in 1880

See more words from the same year

Keep scrolling for more

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 \

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

Comments on pathogen

What made you want to look up pathogen? Please tell us where you read or heard it (including the quote, if possible).


playful or foolish behavior

Get Word of the Day daily email!

Test Your Vocabulary

Autumn Words of the Day 2018

  • a-top-down-image-of-road-through-an-autumn-forest
  • Which is a synonym of fugacious?
How Strong Is Your Vocabulary?

Test your vocabulary with our 10-question quiz!


Test Your Knowledge - and learn some interesting things along the way.


Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!