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

This most recent study shows that by studying how a virus works, researchers can learn more about cellular machinery relevant not only to infectious diseases, but also metabolic diseases and cancer.

From Science Daily

The study also identified increased risks of mortality associated with several causes such as respiratory, circulatory and digestive system disorders; nervous system, endocrine and infectious diseases; cancers; and congenital malformations.

From Science Daily

“I could go on there for 15 minutes and I would know what the trending papers in infectious diseases and virology were just by looking at the timeline,” says Emory University virologist Boghuma Titanji.

From Science Magazine

“His bright smile, infectious laugh and kind heart made you want to be near him,” she wrote Sunday on Instagram.

From Los Angeles Times

“Stalin’s purges were worse than any plague or infectious disease,” Zeldovich writes.

From Salon

Related Words

• contagious
• toxic
• virulent