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

Some experts have questioned the policy shift, since there is no new science strongly defining COVID’s contagious period by an active fever. —Saad B. Omer, The Mercury News, 27 Mar. 2024

The trick here is to sauté the mirepoix until the flavors bloom — and are at their most contagious. —Michelle Huneven, Los Angeles Times, 27 Mar. 2024

Measles cases that turned up in at least three states this year were linked to visits to Florida, federal and state investigators concluded, shedding light on some of the early infections that have fueled an uptick of the highly contagious virus. —Alexander Tin, CBS News, 22 Mar. 2024

Measles is highly contagious, and according to the Cincinnati Health Department, anyone who attended the March 8 show or was in the building for up to two hours after the show ended may have been exposed to measles. —Haadiza Ogwude, The Enquirer, 15 Mar. 2024

The virus is so contagious that 90% people who are unvaccinated and exposed will become infected. —Kristen Jordan Shamus, Detroit Free Press, 10 Mar. 2024

Individuals are contagious during this initial phase, which is prior to the rash appearing. —Kristen Jordan Shamus, Detroit Free Press, 21 Mar. 2024

According to the American Academy of Dermatology, about 7.5 million people in the United States have psoriasis, which is not contagious and can be exacerbated by stress. —USA TODAY, 20 Mar. 2024

Measles, a highly contagious but preventable disease, is resurging in pockets of the United States, a warning of the dangers of the strengthening anti-vaccine movement. —Apoorva Mandavilli, New York Times, 20 Mar. 2024

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 abortion
• contagious disease

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