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

Other Words from contagious Synonyms & Antonyms What is the Difference Between contagious and infectious? More Example Sentences Learn More about contagious

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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.

Recent Examples on the Web

Within days, a few dozen hogs tested positive for a deadly and highly contagious virus, and more than 19,000 pigs in the vicinity were slaughtered. — WSJ, "After Devastating China, African Swine Fever Threatens to Go Global," 25 Apr. 2019 Before the fashion show, Robbie Gordy from Christie’s New York and Marti Gould Cummings commanded the live auction with bawdy humor and contagious enthusiasm. — Ian Malone, Vogue, "This Year’s Jeffrey Fashion Cares Event Unfolded in Spectacular Fashion," 11 Apr. 2019 Wow's contagious business model hastened its unraveling. — Sam Blum, Popular Mechanics, "Are the Discount Airlines Doomed?," 29 Mar. 2019 Swimmers in Illinois are being warned after a person who visited a public pool tested positive for a highly contagious parasite. — Alexandria Hein, Fox News, "Swimmers warned after diarrhea-causing parasite confirmed in Illinois public pool," 19 Sep. 2018 Bravery is contagious, and indeed the driving force behind the #MeToo movement. — Dylan Scott, Vox, "The 7 most important moments from Christine Blasey Ford’s Senate testimony," 27 Sep. 2018 In addition to her killer frame and contagious smile, Arias has become known for her unapologetic and unconventional workouts in airports, staircases, and hotel rooms. — Akili King, Vogue, "With Followers Like Gabrielle Union and SZA, Health Coach Massy Arias Pushes the Boundaries of a Gym Routine," 15 Feb. 2019 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

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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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

See the full definition for contagious in the English Language Learners Dictionary

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

2 : bearing contagion many persons…are contagious long before they are aware of the presence of their disease — Journal of the American Medical Association

3 : used for contagious diseases a contagious ward