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 contagious intestinal illness contagious skin rash contagious viruses — see also contagious disease
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 But the pandemic further complicates HHS’s ability to house children because rooms must have more space so not to spread the highly contagious virus. Anna Giaritelli, Washington Examiner, "Left and Right furious over Biden border holding facility for minors — here's what you need to know," 25 Feb. 2021 Cases of a more contagious virus variant first found in Britain are doubling roughly every 10 days in the United States. New York Times, "Americans Must Tighten Up, or Double Up, Their Masks, C.D.C. Says," 10 Feb. 2021 The one-dose option worked better in the U.S. — 72% effective against moderate to severe COVID-19 — compared with 66% in Latin America and 57% in South Africa, where a more contagious mutant virus is spreading. Lauran Neergaard, Anchorage Daily News, "Johnson & Johnson asks US regulators to approve its one-shot COVID-19 vaccine," 5 Feb. 2021 The vaccine worked better in the U.S. — 72% effective against moderate to severe COVID-19 — compared with 66% in Latin America and 57% in South Africa, where a more contagious mutant virus is spreading. Lauran Neergaard And Linda A. Johnson, Star Tribune, "'Simple is beautiful': One-shot vaccine proves effective," 29 Jan. 2021 Society has disappeared because of a highly contagious virus. Brian Tallerico, Vulture, "The 40 Best Horror Movies on Amazon Prime," 24 Jan. 2021 The famous example is fainting can sometimes seem to be contagious. The Politics Of Everything, The New Republic, "Transcript: The Unsolved Mystery of Havana Syndrome," 3 Feb. 2021 The state gave little other information, citing privacy concerns, though Traxler said neither of the people was contagious any longer. Michelle Liu, Anchorage Daily News, "Virus variant from South Africa detected in US for 1st time," 29 Jan. 2021 Without widespread testing available even to hospitals, patients were assumed to be contagious. Elizabeth Cooney, STAT, "Elective, but not optional: Orthopedic patients eagerly await surgeries delayed by Covid-19," 27 Jan. 2021

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

Middle English, "contaminating, communicable," borrowed from Anglo-French & Late Latin; Anglo-French, borrowed from Late Latin contāgiōsus, from Latin contāgiō "contact, contagion" + -ōsus -ous

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Time Traveler for contagious

Time Traveler

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

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Statistics for contagious

Last Updated

1 Mar 2021

Cite this Entry

“Contagious.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/contagious. Accessed 6 Mar. 2021.

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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
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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