Definition of contagious in English:



  • 1(of a disease) spread from one person or organism to another, typically by direct contact.

    ‘a contagious disease’
    ‘it is a relatively new disease and very contagious’
    • ‘TB is a contagious disease that spreads through the air.’
    • ‘And each child who isn't immunized gives these highly contagious diseases one more chance to spread.’
    • ‘Rubella is a mild, highly contagious illness that is caused by a virus.’
    • ‘Many parents assume that any kind of stomach upset in a child is the result of a contagious illness when the real culprit is simple indigestion or constipation.’
    • ‘Measles, mumps, and rubella are all serious contagious diseases that spread rapidly, especially in populations without immunity.’
    • ‘The epidemic peaked because contagious disease epidemics always do.’
    • ‘Although rheumatic fever is not contagious, strep throat is.’
    • ‘As flocks of sheep return home this month from winter grazing the lowlands of Pembrokeshire, farmers are being warned to be vigilant against the spread of a highly contagious disease.’
    • ‘As a matter of fact, I don't worry at all about the spread of a contagious disease like SARS.’
    • ‘HIV is a lethal contagious disease spread by contact with blood and body fluids.’
    • ‘The closures aim to prevent the accidental spread of the highly contagious disease and operates until 8am on Saturday, March 17.’
    • ‘The spread of contagious disease from the body was continuing to infect our people and it was killing them.’
    • ‘Group A streptococcal infections that cause scarlet fever are contagious.’
    • ‘A respiratory viral infection is a contagious illness that can affect your respiratory tract and cause other symptoms.’
    • ‘These crowded conditions encourage the spread of contagious illnesses among the child silk workers.’
    • ‘Traditional externalities, such as limiting the spread of contagious diseases, explain little of modern government involvement with health.’
    • ‘The purpose of the legislation was to protect against the animals developing and spreading contagious disease.’
    • ‘This is especially important because children may have been exposed to contagious illnesses such as chicken pox or may have recently received immunizations.’
    • ‘Initially, medical experts worked to contain the spread of contagious diseases.’
    • ‘Meanwhile, the contagious disease would spread, leading to widespread illness and public panic.’
    infectious, communicable, transmittable, transmissible, transferable, spreadable
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    1. 1.1 (of a person) having a disease that can be transmitted by contact with other people.
      ‘precautions are taken with anyone who seems contagious’
      • ‘After treatment, a person is still contagious for 2-4 hours.’
      • ‘A person is contagious for 2 to 7 days after symptoms appear.’
      • ‘So they come back to work, when in fact, maybe they should be out for a week to two weeks because they are still contagious.’
      • ‘New cases and potentially contagious patients are identified through proper use and interpretation of the tuberculin skin test.’
      • ‘The person is contagious to others until all of the scabs have fallen off.’
      • ‘A few parents turned their children away from us, as if we were contagious, harmful on sight.’
      • ‘Your child should stay home from school or daycare if he is contagious.’
      • ‘Research suggested that to be at risk from infection spread by coughs or sneezes it was necessary to sit within two rows of a contagious passenger for more than eight hours.’
      • ‘The physician must evaluate whether the risk of treating the contagious patient exceeds the level of risk that he is usually and habitually willing to take.’
      • ‘Victims are contagious once symptoms have appeared and possibly for a short time before they develop fever.’
      • ‘But it is a general hospital with no specialized contagious-disease division, and it had never before treated such contagious patients.’
      • ‘A person is most contagious from about 1 day before the salivary glands swell, to at least another 3 days after the swelling began.’
      • ‘Lice aren't dangerous and they don't spread disease, but they are contagious and can just be downright annoying.’
      • ‘Celine's TB is not active, which means she's not contagious, but she has to start treatment that could take up to a year.’
      • ‘They meet people with leprosy who are ostracized even by the doctors who know they are not contagious.’
      • ‘The person is contagious until the last blister has scabbed over.’
      • ‘Patients are more contagious than carriers but carriers keep the disease alive.’
      • ‘It will take up to ten days for the onset of symptoms, during which time the person is highly contagious.’
      • ‘Even if a person with HIV doesn't feel or look sick, he is still contagious.’
      • ‘A person is most contagious just before the fever starts to about 4 days after the rash appears.’
      plague-like, communicable, epidemic, pestilent, dangerous, injurious, harmful, destructive, virulent, pernicious
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  • 2(of an emotion, feeling, or attitude) likely to spread to and affect others.

    ‘her enthusiasm is contagious’
    • ‘He speaks about his Oxford crew with an immutable and contagious excitement.’
    • ‘His enthusiasm is contagious and the book is full of information, but his approach is overly academic.’
    • ‘He sparks with highly contagious enthusiasm while sipping his beer.’
    • ‘Thanks to his very persuasive speech and contagious enthusiasm, he won with nearly 80 per cent of the votes.’
    • ‘They love car rides, of course, and their enthusiasm is strangely contagious.’
    • ‘And in that regard the former professor's confidence is as contagious as his enthusiasm.’
    • ‘Together, they argue that emotions are contagious, and a successful leader is one from whom people ‘catch’ positive feelings.’
    • ‘Dawn's passion is contagious, and Ian has his own way of being persuasive.’
    • ‘Pan's enthusiasm was contagious and soon some of his friends, including his girlfriend Lisa, had their ears pierced.’
    • ‘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.’
    • ‘And they looked like they were having fun and that fun was contagious.’
    • ‘Attitudes are contagious, and how we behave does influence others.’
    • ‘The enthusiasm is contagious as 200 students of the team prepare for their grand event.’
    • ‘It built up enthusiasm, and enthusiasm is contagious.’
    • ‘I appeared to be a never-ending foundation of contagious emotion.’
    • ‘It took no time to spread here, feeding off a contagious love of popularity.’
    • ‘He exudes a contagious enthusiasm when he discusses what drives him to write.’
    • ‘The crowd didn't seem to know much about her music, but her contagious enthusiasm soon had much of the audience dancing.’
    • ‘I realized that people were living on the edge, and feelings were very contagious in groups.’


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 humour or optimism


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