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 Word Forms

• 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

"Beyond his musicianship, Clem was a source of inspiration both on and off the stage. His vibrant spirit, infectious enthusiasm and rock solid work ethic touched everyone who had the privilege of knowing him."

From BBC

The singer's infectious energy and knotty pop-rock songs have been picking up new fans in every city.

From BBC

Thus, gutting the Department of Health and Human Services’ infectious disease research and forcing out the FDA’s chief vaccine expert is exactly what it looks like: an effort to see that more Americans die.

From Salon

They can also detect tuberculosis, an infectious disease that commonly affects the lungs, far quicker than it would be found in a lab using conventional microscopy, Apopo says.

From BBC

In an online fundraiser to help cover Buzzetta’s medical fees and funeral expenses, her family described her as determined, tenacious, insightful and kind, with a crazy sense of humor and an infectious laugh.

From Los Angeles Times

Related Words

• contagious
• toxic
• virulent