contagious

adjective
con·​ta·​gious | \kən-ˈtā-jəs \

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

Debora's contagious smile will be remembered by her mother Joanne Pitz, her sister Catherine and husband Bobby Leighton, her niece and nephew Ashley and Matthew Leighton, and her caregivers Sheri (Auntie), Kristy and Steven. Hartford Courant, courant.com, "Debora Pitz," 21 June 2018 Kaylee flashed a contagious smile at the end of each song during Tuesday's session. Robert Gundran, azcentral, "The power of music: Teen leukemia patient at Mesa hospital uses ukulele to stay positive," 20 Mar. 2018 She will be especially remembered for her contagious smile and family loyalty. Sun-Sentinel.com, "Deaths in South Florida: 2/22," 22 Feb. 2018 Six people have died from the contagious virus, Dr. Jeff Howard, Kentucky Commissioner of Public Health, told the Courier Journal on Wednesday. Beth Warren, The Courier-Journal, "Deadly hepatitis A outbreak now the worst in Kentucky's history," 27 June 2018 Hepatitis A is a very contagious virus that causes liver inflammation that can be deadly. Kristen Jordan Shamus, Detroit Free Press, "Michigan's hepatitis A outbreak is worst in U.S. What you need to know.," 27 May 2018 Measles is a highly contagious virus that is spread through the air when someone coughs or sneezes. Catherine Rentz, baltimoresun.com, "Health officials confirm measles case in Maryland," 24 May 2018 The Nipah virus is a highly contagious and deadly virus that was first identified in 1999 when pig farmers in Malaysia and Singapore became very sick. Alexandra Sifferlin, Time, "What You Should Know About the Nipah Virus Outbreak," 22 May 2018 Ebola is an incredibly contagious virus which causes the sudden onset of symptoms including fever, fatigue and muscle pain within two to 21 days after infection. Joshua Berlinger, CNN, "Experimental Ebola vaccine to be distributed in Congo," 21 May 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

4 Nov 2018

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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 \

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 \

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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