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contagious

adjective
con·​ta·​gious | \ kən-ˈtā-jəs How to pronounce contagious (audio) \

Definition of contagious

1 : transmissible by direct or indirect contact with an infected person contagious diseases
2 : bearing contagion contagious people
3 : used for contagious diseases a contagious ward
4 : exciting similar emotions or conduct in others contagious enthusiasm contagious laughter
Other Words from contagious Synonyms & Antonyms What is the Difference Between contagious and infectious? More Example Sentences Learn More about contagious

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Other Words from contagious

contagiously adverb
contagiousness noun

What is the Difference Between contagious and infectious?

The words contagious and infectious can be confusing because they do not designate wholly distinct categories; something is not either contagious or infectious.

Essentially, infectious diseases and contagious diseases are caused by disease-producing agents such as bacteria and viruses, but they differ in that contagious diseases can be spread to other people by direct or indirect contact.

Anything contagious, such as the flu, is always automatically infectious: if you can catch it from someone, it's being passed to you via an infectious agent, which is the thing that gets you sick—usually a virus or a bacteria.

The reverse, however, isn't true. Just because something is infectious does not mean it's contagious. Food poisoning, for example, is infectious but not contagious: food can be contaminated with a bacteria (an infectious agent) that makes you sick, but you can't give your food poisoning to someone else by shaking their hand or even giving them a kiss.

Both contagious and infectious are also used figuratively, often in much happier contexts: laughter can be contagious; someone's enthusiasm can be infectious. While both words are used figuratively of both pleasant and unpleasant things, contagious is more often chosen for the unpleasant, as when it's grumpiness or fear that seems to be spreading.

Examples of contagious in a Sentence

It's a highly contagious virus. I have a cold and I'm still contagious. I'm sick, but the doctor says I'm not contagious.
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Recent Examples on the Web

 Those outbreaks are, in large part, thanks to to just how contagious measles is. — Amanda Macmillan, Health.com, "So There's a Measles Outbreak Near You. How Worried Should You Be?," 5 Sep. 2019 In the United States, debilitating, deadly and incredibly contagious diseases have been nearly eliminated by vaccines. — Los Angeles Times, "Dr. Bob Sears’ views on vaccines have inspired loyal followers — and a crush of criticism," 3 Sep. 2019 In Montana, former governor Brian Schweitzer and state legislators over the years have urged Yellowstone National Park to allow bison hunting to keep a rare but contagious bacterial infection in check. — Felicia Fonseca, Washington Post, "Grand Canyon to make second run at corralling bison herd," 2 Sep. 2019 For those of us lucky enough to have known him, Adam radiated a contagious exuberance for life and also personified the very definition of a true friend. — Eric Todisco, PEOPLE.com, "Mandy Moore Remembers Ex Adam 'DJ AM' Goldstein on 10th Anniversary of His Death: 'Miss You Every Day'," 28 Aug. 2019 Pertussis, or whooping cough, is a very contagious bacterial infection spread from person to person by coughing, sneezing, or even sharing breathing space. — Sabrina Adams, SELF, "I Treat Infants With Whooping Cough in the ICU—Of Course I’m Pro-Vaccine," 26 Aug. 2019 Many vaccine-preventable diseases are very contagious, passing easily among people inside a school. — al, "Unvaccinated students are clustered in private schools," 9 Aug. 2019 Much like your common cold, viral pink eye is incredibly contagious. — Rebecca Dancer, Allure, "What Exactly Is Pink Eye, and How Do You Treat It?," 26 July 2019 Twins Mark and Marcus Carter have the numbers growing, and the intensity contagious as program's rebuilding blocks get bigger. — Richard Obert, azcentral, "Arizona high school football: Previewing regions 5A Metro, 5A Northeast Valley," 11 Aug. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'contagious.' 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 contagious

14th century, in the meaning defined at sense 1

History and Etymology for contagious

see contagion

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More Definitions for contagious

contagious

adjective
How to pronounce contagious (audio)

English Language Learners Definition of contagious

: able to be passed from one person or animal to another by touching
: having a sickness that can be passed to someone else by touching
: capable of being easily spread to others : causing other people to feel or act a similar way

See the full definition for contagious in the English Language Learners Dictionary

contagious

adjective
con·​ta·​gious | \ kən-ˈtā-jəs How to pronounce contagious (audio) \

Kids Definition of contagious

1 : able to be passed from one individual to another through contact a contagious disease
2 : having a sickness that can be passed to someone else
3 : causing other people to feel or act a similar way a contagious laugh

contagious

adjective
con·​ta·​gious | \ -jəs How to pronounce contagious (audio) \

Medical Definition of contagious

1 : communicable by contact tuberculosis in the contagious stage
2 : bearing contagion many persons…are contagious long before they are aware of the presence of their disease — Journal of the American Medical Association
3 : used for contagious diseases a contagious ward

Other Words from contagious

contagiously adverb

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