infectious

[ in-fek-shuhs ]

adjective

1. communicable by infection, as from one person to another or from one part of the body to another:

   infectious diseases.

   Synonyms: catching

2. causing or communicating infection.
3. tending to spread from one to another:

   infectious laughter.

4. Law. capable of contaminating with illegality; exposing to seizure or forfeiture.
5. Obsolete. diseased.

infectious

/ ɪnˈfɛkʃəs /

adjective

1. (of a disease) capable of being transmitted Compare contagious
2. (of a disease) caused by microorganisms, such as bacteria, viruses, or protozoa
3. causing or transmitting infection
4. tending or apt to spread, as from one person to another

   infectious mirth

5. international law
   1. tainting or capable of tainting with illegality
   2. rendering liable to seizure or forfeiture

infectious

/ ĭn-fĕk′shəs /

1. Capable of causing infection.
2. See Note at contagious

Derived Forms

• inˈfectiousness, noun
• inˈfectiously, adverb

Other Words From

• in·fectious·ly adverb
• in·fectious·ness noun
• nonin·fectious adjective
• nonin·fectious·ly adverb
• nonin·fectious·ness noun
• unin·fectious adjective
• unin·fectious·ly adverb
• unin·fectious·ness noun

Word History and Origins

Origin of infectious¹

First recorded in 1535–45; infect(ion) + -ious

Synonym Study

See contagious.

Example Sentences

If you’re sleeping in a bed with them, sharing your home with them, and so on, you already have a decent risk of swapping the virus, or really any other infectious disease.

From Popular-Science

Monica Gandhi, an infectious disease doctor and a professor of medicine at the University of California San Francisco, said the focus on transmission in the context of Covid-19 vaccines can be misleading when comparing them to other vaccines.

From Vox

That could pose a problem even for vaccinated adults, says Mobeen Rathore, an infectious disease specialist and epidemiologist at the University of Florida College of Medicine.

From MIT Technology Review

As we learn how to address current and future pandemics, it is worth understanding what we learned from the great infectious disease fights of the past.

From Vox

That’s especially true now as new, more infectious coronavirus variants await — putting us at risk of an even bigger surge than the one we saw during the holiday season if we ease up.

From Vox

For most infectious, the amount is 100 or even 1,000 times that.

From The Daily Beast

Although bats may have creeped us out for centuries, their links to emerging infectious diseases are much more recent.

From The Daily Beast

In Malaysia and Bangladesh, a devastating infectious neurological disease emerged just a few years after Hendra.

From The Daily Beast

The only existing study, printed in the Journal of Infectious Diseases in 1999, leaves scientists with the same questions.

From The Daily Beast

Adam Lausing, an infectious disease researcher at the University of Michigan, emphasized that Ebola is not a respiratory disease.

From The Daily Beast

The last movement had the infectious gayety that Mozart's things often have, with a magnificent cadenza by himself.

From Project Gutenberg

The infectious diseases in which leukocytosis is absent (p. 160) often cause a slight decrease of leukocytes.

From Project Gutenberg

(b) Acute infectious diseases, especially rheumatism and typhoid fever.

From Project Gutenberg

Predominance of polymorphonuclear leukocytes (pus-corpuscles) points to an acute infectious process (Fig. 117).

From Project Gutenberg

The usual cause of acute infectious conjunctivitis, especially in cities, seems to be the Koch-Weeks bacillus.

From Project Gutenberg

Related Words

• contagious
• toxic
• virulent