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

1. Capable of causing infection.

2. See Note at contagious

Other Word Forms

• infectiously adverb
• infectiousness noun
• noninfectious adjective
• noninfectiously adverb
• noninfectiousness noun
• uninfectious adjective
• uninfectiously adverb
• uninfectiousness noun

Word History and Origins

Origin of infectious¹

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

Synonym Study

See contagious.

Example Sentences

"We will do everything again to be infectious, there's no problem. I'm sure we will get everyone going - it is on us. But tonight I was a little underwhelmed."

Read more on BBC

Many people in the U.S. have asymptomatic hepatitis B, says O’Leary, a pediatric infectious disease specialist at the University of Colorado Anschutz Medical Campus and Children’s Hospital Colorado in Aurora.

Read more on The Wall Street Journal

Vaccination is one of public health’s biggest tools for preventing and stopping infectious disease, he said—and given Kennedy’s stance, Osterholm was particularly worried about the ACIP.

Read more on The Wall Street Journal

The singer herself billed the album as a bombastic, infectious slate of pop standards, one that would feel as exciting as her Eras Tour shows.

Read more on The Wall Street Journal

Now, Marks will be Lilly’s senior vice president of molecule discovery and head of infectious disease.

Read more on Barron's

Related Words

• contagious 
• toxic 
• virulent