contagious

adjective

con·​ta·​gious kən-ˈtā-jəs 

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

contagiously adverb

contagiousness noun

Did you know?

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.

Synonyms

• catching
• communicable
• pestilent
• transmissible
• transmittable

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

Because emotions can be contagious and spread throughout your organization. —Expert Panel, Forbes, 29 Nov. 2023

Experts said other diseases are at risk of spreading in Gaza, including cholera, which is a type of highly contagious, life-threatening, diarrheal illness spread through contaminated water. —Dr. Jade Cobern, ABC News, 18 Nov. 2023

Researchers have demonstrated that gene editing could someday be used to make chickens resistant to the avian flu—a contagious virus that led to the deaths of 131 million domestic poultry in 2022, either due to infection or culling to stop the spread. —Will Sullivan, Smithsonian Magazine, 13 Oct. 2023

The flu and the common cold are contagious illnesses that affect your respiratory system, but they're caused by different types of viruses. —Katie Liu, Discover Magazine, 16 Nov. 2023

There has been some chatter online about being contagious after getting your COVID-19 vaccine, but doctors stress this isn’t possible. —Korin Miller Published, Verywell Health, 15 Nov. 2023

Up to 13 million people in the U.S. have latent tuberculosis infections, meaning the bacteria is inactive and the infected person doesn’t have symptoms and isn’t contagious. —Aria Bendix, NBC News, 10 Nov. 2023

Alternative methods of instruction days -- authorized by a 2017 state law and widely used in recent years -- permitted students and educators to work from their homes on days when inclement weather, contagious illness and utility outages caused a school campus or school district to be closed. —Cynthia Howell, Arkansas Online, 8 Nov. 2023

Word of mouth about the label, which has achieved cult status, has been contagious between attendees. —Jasmine Damian, Los Angeles Times, 3 Nov. 2023

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Word History

Etymology

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

First Known Use

14th century, in the meaning defined at sense 1

Phrases Containing contagious

• contagious disease
• contagious abortion

• contagious disease
• contagious abortion

Kids Definition

contagious

adjective

con·​ta·​gious kən-ˈtā-jəs 

1

a

: able to be passed on by contact between individuals

colds are contagious

contagious diseases

b

: capable of passing on a contagious disease to another

he is contagious

2

: so pleasantly irresistible as to be picked up by one person after another

your enthusiasm is contagious

Etymology

Middle English contagious "likely to be passed on through contact," from early French contagieus (same meaning), derived from Latin contingere "to have contact with, affect, happen" — related to contact, contingent

Medical Definition

contagious

adjective

con·​ta·​gious -jəs 

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

contagiously adverb

contagiousness noun