Definition of parasite in US English:

parasite

noun

  • 1An organism that lives in or on an organism of another species (its host) and benefits by deriving nutrients at the other's expense.

    Parasites exist in huge variety, including animals, plants, and microorganisms. They may live as ectoparasites on the surface of the host (e.g., arthropods such as ticks, mites, lice, fleas, and many insects infesting plants) or as endoparasites in the gut or tissues (e.g., many kinds of worm), and cause varying degrees of damage or disease to the host

    ‘the parasite attaches itself to the mouths of fishes’
    ‘an intestinal parasite of cattle’
    • ‘Some water molds are parasites on other organisms; they may grow on the scales or eggs of fish, or on amphibians.’
    • ‘Another constraint on ejection is the close resemblance of eggs of hosts and parasites.’
    • ‘Only the latter could be accepted as evidence of coevolution between the parasite and a particular host.’
    • ‘An implicit requirement is that parasites and their hosts match up to some degree.’
    • ‘By contrast, infection will tend to limit nitrate accumulation in the host roots as a result of nitrate transfer from host roots to the parasite.’
    • ‘Because host nestlings remain in the nest, the parasite must compete with host nestlings for food.’
    • ‘These genes are essentially immune system genes and defend the host organism from parasites.’
    • ‘The relationship between host and parasite is not a simple one, and just as the parasite affects the host, so the host affects the parasite.’
    • ‘We consider three rejection scenarios by a host of a nonevicting parasite.’
    • ‘Another hallmark of parasites is that hosts often evolve defenses against them.’
    • ‘Other typically much larger organisms, including parasites such as lice, worms and scabies can also spread from person to person.’
    • ‘After all, more than half the species on Earth are parasites, and most organisms are host to a number of them.’
    • ‘Host radiation allows a parasite to expand its ecological niche by adapting to one or more novel hosts.’
    • ‘Detrimental effects on hosts can occur at several stages of the parasite's life cycle.’
    • ‘The most sophisticated defense system used by hosts against parasites is the immune system.’
    • ‘All parental hosts of heterospecific brood parasites must pay the cost of rearing non-kin.’
    • ‘If hosts and parasites are coevolving, this can drive the rapid divergence of amino acid sequences.’
    • ‘Good places for reliable encounters are where small fish act as barbers to their hosts, cleaning away parasites from their skin.’
    • ‘Selection has been intense as the parasites are host specific and the drugs are very widely used.’
    • ‘There are many species of parasites and disease organisms that infect dogs.’
  • 2derogatory A person who habitually relies on or exploits others and gives nothing in return.

    ‘the capitalist is really a parasite on the workers’
    • ‘They are literary parasites, the enemies of creativity and imagination.’
    • ‘These neocon pseudofascists are like a parasite using the host Republican party to attain their ends.’
    • ‘Every governmental attempt to ameliorate poverty seems to attract its own breed of parasite and leech.’
    • ‘They were like parasites, leeching on to him, just wanting him to do this or that, or to torture him.’
    • ‘All workers were oppressed, all middle class people parasites.’
    • ‘It was in essence a parasite leeching on to Western decadence and lack of will.’
    • ‘And that's what it will come to, for the council workers and other public sector parasites.’
    • ‘They are all a pack of bludgers and parasites who pay no taxes but spend ours.’
    • ‘In the unionists' imagination, the rich are social parasites living lives of leisure on inherited wealth.’
    • ‘MPs, councillors and all their cronies are nothing more than scroungers, spongers, parasites.’
    • ‘I've repented my sins to Sepp and he has led me away from the bloodsuckers and parasites that threatened to dissolve my soul.’
    hanger-on, cadger, leech, passenger, drone
    View synonyms

Origin

Mid 16th century: via Latin from Greek parasitos ‘(person) eating at another's table’, from para- ‘alongside’ + sitos ‘food’.

Pronunciation

parasite

/ˈpɛrəˌsaɪt//ˈperəˌsīt/