Definition of contagious in English:

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Pronunciation: /kənˈtājəs/


1(Of a disease) spread from one person or organism to another by direct or indirect contact: a contagious infection
More example sentences
  • Measles, mumps, and rubella are all serious contagious diseases that spread rapidly, especially in populations without immunity.
  • HIV is a lethal contagious disease spread by contact with blood and body fluids.
  • As a matter of fact, I don't worry at all about the spread of a contagious disease like SARS.
infectious, communicable, transmittable, transmissible, spreadable
informal catching
dated infective
1.1(Of a person or animal) likely to transmit a disease by contact with other people or animals.
Example sentences
  • A person is contagious for 2 to 7 days after symptoms appear.
  • After treatment, a person is still contagious for 2-4 hours.
  • A person is most contagious from about 1 day before the salivary glands swell, to at least another 3 days after the swelling began.
2(Of an emotion, feeling, or attitude) likely to spread to and affect others: her enthusiasm is contagious
More example sentences
  • I appeared to be a never-ending foundation of contagious emotion.
  • Estrella couldn't help but laugh herself, as his attitude was contagious.
  • I had never seen him so scared in my life, and the feeling was contagious.


Strictly, a contagious disease is one transmitted by physical contact, whereas an infectious one is transmitted via microorganisms in the air or water. In practice, there is little or no difference in meaning between contagious and infectious when applied to disease or its spread. In figurative senses, contagious may describe the spread of good things such as laughter and enthusiasm or bad ones such as violence or panic, whereas infectious usually refers to the spread of positive things, such as good humor or optimism.



Pronunciation: /kənˈtājəslē/
Example sentences
  • What the critics said: ‘Gibson seems all but inflated with helium throughout, which contagiously lifts everyone else around him.’
  • I looked back at her and, through the tears in her eyes she smiled her contagiously peaceful smile and, once more, reminded me why it was so difficult to have broken up with her.
  • These endophytes are not known to spread contagiously but instead are disseminated through seeds and by vegetative growth of the host.


Pronunciation: /kənˈtājəsnəs/
Example sentences
  • The models also included information about the flu virus, such as the possible contagiousness of an infected person.
  • He correctly identified seven of the 12 cranial nerves, discovered the valves of the heart, recognized the contagiousness of tuberculosis, and the possible spread of rabies via dogs.
  • Antibiotics shorten the period of contagiousness to 5 days following the start of antibiotic treatment.


Late Middle English: from late Latin contagiosus, from contagio (see contagion).

Words that rhyme with contagious

advantageous, courageous, outrageous, rampageous

For editors and proofreaders

Syllabification: con·ta·gious

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