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

Dr. Elizabeth Hudson, the regional physician chief of infectious diseases for Kaiser Permanente Southern California, said data continue to show an increase in coronavirus cases.

From Los Angeles Times

Founded in 1946, the CDC tracks emerging infectious diseases like Covid and is also tasked with tackling long-term or chronic conditions such as heart disease and cancer.

From BBC

“Florida has seen spikes in infectious diseases like measles, diseases we had virtually eliminated before Ladapo took office. This decision… makes Floridians less safe.”

From Salon

Dr. Elizabeth Hudson, the regional chief of infectious diseases at Kaiser Permanente Southern California, said she received many calls related to outpatient cases of COVID-19 while on call over the Labor Day weekend.

From Los Angeles Times

Los Angeles City Councilmember John Lee, who represents the West Valley, called the volunteers’ work “infectious” and credits the group for making his council district look cleaner than other parts of the city.

From Los Angeles Times

Related Words

• contagious 
• toxic 
• virulent