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

But his enthusiasm is infectious, and it is clear how much inspiration he draws from his fellow coaches.

From BBC

"People are so stressed these days, so these events are a good thing. Because happiness is infectious."

From BBC

"Other runners were stopping and dancing with him. It was quite infectious."

From BBC

In the last year, some of music's biggest and most recognizable faces have released chart-topping, infectious pop music.

From Salon

But he is rapidly inching closer toward influencing the federal response to infectious disease, vaccines and public health — which many scientists say would be detrimental to the nation.

From Salon

Related Words

• contagious
• toxic
• virulent