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

In a 2011 study conducted by the Centers for Disease Control, 97% of nail salon footbaths tested contained the bacteria Mycobacterium fortuitum, a highly contagious bug that can cause boils on the skin. Meghan Overdeep, Southern Living, "The Truth About Germs Hiding in Pedicure Tubs Will Ruin Your Day," 14 Mar. 2018 The sound mix during their turn onstage amplified their weathered voices into stridency, but nevertheless their joy was contagious and their harmonies as stirring as ever. Zoë Madonna, BostonGlobe.com, "With big assists from Moreno and Giddens, the Pops envisions a welcoming America," 5 July 2018 How smiling is contagious and why to do more of it. Karen Pearlman, sandiegouniontribune.com, "TedX event in El Cajon showcases students' ideas, hearts," 23 Apr. 2018 Unlike the flu, Legionnaires' is not contagious and does not have a particular season of high activity, Marquez said. Mayra Cruz, Houston Chronicle, "Cypress woman confirmed to have Legionnaires' disease," 15 Feb. 2018 Since public health organizations don't track pneumonia deaths because that illness is not contagious, the deaths are attributed to influenza. Julie Washington, cleveland.com, "Cold or flu? Here's how to tell, plus your flu vaccine questions answered," 23 Jan. 2018 According to the Centers for Disease Control, Erin says, the Lyme is not contagious. John Whisler, San Antonio Express-News, "Wife’s diagnosis adds twist to golfer Jimmy Walker’s Lyme disease story," 10 Jan. 2018 The devil, Tasmania’s other iconic species, is suffering from a contagious and fatal facial cancer that essentially clones itself when the devils bite one another’s faces. Brooke Jarvis, The New Yorker, "The Obsessive Search for the Tasmanian Tiger," 16 Jan. 2012 Every single song is a bop, and their energy onstage is contagious. Chris Varias, Cincinnati.com, "10 not-to-miss bands at final Vans Warped Tour," 11 July 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

9 Sep 2018

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Time Traveler for contagious

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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