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

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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

The condition is a (usually) mild yet contagious viral infection caused by the coxsackievirus, which comes with mouth sores and a rash on the hands and feet, according to the Mayo Clinic. Korin Miller, SELF, "This Baseball Star Is Out Sick With Hand, Foot, and Mouth Disease," 26 July 2018 Hepatitis A causes a highly contagious liver infection. Barbara Henry, sandiegouniontribune.com, "Encinitas agrees to continue funding for temporary restrooms," 18 June 2018 Measles is a highly contagious viral infection that can spread rapidly among people who have not been vaccinated. Maria Clark, NOLA.com, "Second measles cases confirmed in New Orleans, health officials say," 11 May 2018 The department said several people have tested positive for norovirus, a highly contagious infection that causes inflammation of the stomach and/or intestines and results in symptoms including vomiting, diarrhea, nausea, fever and stomach pain. Jamie Ducharme, Time, "Canadian Raw Oysters Are Behind a Norovirus Outbreak in California," 3 May 2018 In a press release, the Macomb County Health Department confirmed that a foodservice worker at the Buffalo Wild Wings at 29287 Mound Road in Warren has been diagnosed with hepatitis A, a highly contagious liver infection. Aleanna Siacon, USA TODAY, "Sick Buffalo Wild Wings employee may have exposed Michigan customers to hepatitis A," 29 Apr. 2018 The flu, or influenza, is a contagious viral infection that usually can be treated at home with rest and fluids. Andy Marso, kansascity, "Kansas takes over as nation’s flu hotspot, according to smart thermometer," 1 Feb. 2018 According to the American Veterinary Medical Association, canine influenza, known as dog flu, is a highly contagious viral infection affecting dogs and also cats. Howard Cohen, miamiherald, "Don’t just worry about your kids. Your dog — or cat — can get the flu, too.," 1 Feb. 2018 Hepatitis A is a highly contagious infection caused by a virus that affects the liver. CBS News, "Up to 2,000 people possibly exposed to hepatitis A at Utah 7-Eleven," 8 Jan. 2018

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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Last Updated

25 Feb 2019

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The first known use of contagious was in the 14th century

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More Definitions for contagious

contagious

adjective

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

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 — compare infectious sense 2
2 : bearing contagion many persons…are contagious long before they are aware of the presence of their diseaseJournal of the American Medical Association
3 : used for contagious diseases a contagious ward

Other Words from contagious

contagiously adverb
contagiousness noun

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