Definition of virus in English:



  • 1An infective agent that typically consists of a nucleic acid molecule in a protein coat, is too small to be seen by light microscopy, and is able to multiply only within the living cells of a host.

    [as modifier] ‘a virus infection’
    • ‘Leucodepletion also reduces transmission rates of other cell associated viruses such as cytomegalovirus.’
    • ‘A large number of viruses emerge from the host cell before it dies.’
    • ‘White blood cells chase bacteria and viruses, preventing us from getting sick.’
    • ‘Bacteriophages are viruses that infect bacteria.’
    • ‘The evolution of a virus within a host has been shown to be strongly influenced by its environment.’
    • ‘Virtually all pathogenic bacteria, viruses and fungi are anaerobic and will be killed by hydrogen peroxide.’
    • ‘Such viruses enter the host cell and then rapidly multiply inside the cell before killing it.’
    • ‘When found outside of host cells, viruses exist as a protein coat or capsid, sometimes enclosed within a membrane.’
    • ‘Among other things, biological agents include bacteria, viruses, fungi, pollen, dust mites and moulds.’
    • ‘The World Health Organization has said that following natural disasters, bacteria and viruses from corpses die within 24 hours.’
    • ‘Bacteria and some viruses multiply and mutate rapidly, and can evolve much more quickly than we can develop new drugs to fight them.’
    • ‘Herpes and other viruses come with protein tool kits of their own.’
    • ‘Bacteriophages fit the definition of parasite to a T. In many cases new viruses multiply inside a host until the bacterium simply rips apart.’
    • ‘A trend that is evident in the table is that viruses that infect bacteria are more tightly packed than the viruses that infect eukaryotic cells.’
    • ‘It may be difficult to recognize the virus within the cells due to the presence of similar sized ribosomes.’
    • ‘Importers want their products cleared quickly but fungi and other plant pathogens like bacteria and viruses don't always like to reveal themselves.’
    • ‘The idea is to insert therapeutic genes directly into a patient's cells, using viruses or other agents as delivery vehicles.’
    • ‘Unfortunately this means that a whole host of bacteria, viruses and prions are just waiting to be levelled at any of us at any time.’
    • ‘All microbes, be it viruses, bacteria, mycoplasma, fungi or parasites interfere in research.’
    • ‘Numerous virulence genes in pathogenic bacteria and viruses have been shown to be under positive selection.’
    1. 1.1An infection or disease caused by a virus.
      • ‘Been off sick with a virus for like AGES!!!’
      • ‘After some months when it became clear that my malady wasn't disappearing like a good virus, this burden fell on my husband.’
      • ‘The most recent problem has been a virus and she comes into the tournament short on match play.’
    2. 1.2A harmful or corrupting influence.
      ‘the virus of cruelty that is latent in all human beings’
  • 2A piece of code that is capable of copying itself and typically has a detrimental effect, such as corrupting the system or destroying data.

    • ‘Specifically, it aims to help businesses understand and protect against the most common IT-related risks, such as viruses.’
    • ‘Opening a file could expose your system to a computer virus or a program that could hijack your modem.’
    • ‘Hewlett-Packard has distributed printer drivers corrupted by a computer virus.’
    • ‘Almost one in every three Internet users in the United States has been hit by either a computer virus or a hacker in the past two years.’
    • ‘A computer virus which affected the operation of Google yesterday is spreading like wildfire.’
    • ‘But on the same day of that announcement, the mighty Google was also the victim of a computer virus that killed the search for most users for hours.’
    • ‘A computer virus or spyware application is sending us automated requests, and it appears that your computer or network has been infected.’
    • ‘The Justice Department has blamed a computer virus for the delay.’
    • ‘So Thomas decided to exact revenge by surreptitiously placing a vicious computer virus on Scott's machine which destroyed his hard drive.’
    • ‘Anyone who has been hit by a computer virus will be doubly wary of unexpected emails in the future that may contain viruses.’
    • ‘Because this malware can be transferred from machine to machine on a removable disk, and requires user interaction to spread, it is, quite simply, a computer virus.’
    • ‘Pennsylvania makes it crime to spread a computer virus.’
    • ‘My car caught a computer virus from my mobile phone.’
    • ‘After his two best friends are shown the door, he hatches a plot with them to steal money from the firm by planting a money-siphoning computer virus within its system’
    • ‘They were unprepared for operations being interrupted by a system crash or the arrival of a computer virus through email.’
    • ‘How do you stop a computer virus from spreading and infecting other computers?’
    • ‘With every announcement of a big computer virus, the number of ‘experts’ double.’
    • ‘Japanese newspaper Daily Yomiuri reports that police suspect that a computer virus might have sucked up this sensitive data and spread it over the Net.’
    • ‘Combine viruses with the scourge of spam and you have two heavy anchors dragging down Irish productivity.’
    • ‘According to media reports, the 2003 Pan American Games have been disrupted by a computer virus.’


Late Middle English (denoting the venom of a snake): from Latin, literally slimy liquid, poison The earlier medical sense, superseded by the current use as a result of improved scientific understanding, was a substance produced in the body as the result of disease, especially one that is capable of infecting others with the same disease.