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

Asian markets may have sold off heavily on Wednesday, but many of the most recent readings on actual growth suggest that macroeconomic weakness isn’t proving contagious in emerging countries. Nathaniel Taplin, WSJ, "Asian Satellites Buck China’s Downward Drift," 5 Sep. 2018 The infection was found to be an isolated case and not contagious to other dolphins or to humans. Bayan Wang, azcentral, "Report: Alia the bottlenose dolphin died of a bacterial infection," 29 June 2018 His passion for life and enjoyment of the moment was contagious to all who spent time with him and people loved to be around him. courant.com, "Sebastian Anthony Santiglia," 31 May 2018 The ringworm disease is not only contagious to other animals, it’s considered a zoonotic disease, meaning that it can be transmitted from animals to humans (and vice versa). Dr. Patty Khuly, miamiherald, "Ringworm not really a worm but a fungus contagious to pets and humans | Miami Herald," 18 May 2018 His work ethic is contagious on the field, in the classroom and during the offseason. Pat Disabato, Daily Southtown, "Baseball notes: Lincoln-Way Central's Brandon Bennitt comes up big and 'will do anything to help the team win'," 3 May 2018 Love to see him shed that and just enjoy playing baseball, because his joy is as contagious as anybody else’s. Dennis Lin, sandiegouniontribune.com, "Ervin Santana pitches complete game, beats Padres," 2 Aug. 2017 The family pickleball obsession seems to be contagious. Jen Murphy, WSJ, "A Tennis Purist Who Became a Pickleball Pro," 19 Jan. 2019 Her smile is contagious, the kind that only belongs to that person in high school who was everyone’s best friend. Candice Benbow, Glamour, "Meet KiKi Layne, the If Beale Street Could Talk Actress Everyone's Talking About," 27 Dec. 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

11 Feb 2019

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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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