Definition of parasite in English:



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

    ‘the parasite attaches itself to the mouths of fishes’
    ‘an intestinal parasite of cattle’
    • ‘Other typically much larger organisms, including parasites such as lice, worms and scabies can also spread from person to person.’
    • ‘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.’
    • ‘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.’
    • ‘If hosts and parasites are coevolving, this can drive the rapid divergence of amino acid sequences.’
    • ‘Detrimental effects on hosts can occur at several stages of the parasite's life cycle.’
    • ‘Some water molds are parasites on other organisms; they may grow on the scales or eggs of fish, or on amphibians.’
    • ‘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.’
    • ‘Good places for reliable encounters are where small fish act as barbers to their hosts, cleaning away parasites from their skin.’
    • ‘All parental hosts of heterospecific brood parasites must pay the cost of rearing non-kin.’
    • ‘Another constraint on ejection is the close resemblance of eggs of hosts and parasites.’
    • ‘The most sophisticated defense system used by hosts against parasites is the immune system.’
    • ‘An implicit requirement is that parasites and their hosts match up to some degree.’
    • ‘These genes are essentially immune system genes and defend the host organism from parasites.’
    • ‘Another hallmark of parasites is that hosts often evolve defenses against them.’
    • ‘Only the latter could be accepted as evidence of coevolution between the parasite and a particular host.’
    • ‘We consider three rejection scenarios by a host of a nonevicting parasite.’
    • ‘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’
    • ‘These neocon pseudofascists are like a parasite using the host Republican party to attain their ends.’
    • ‘I've repented my sins to Sepp and he has led me away from the bloodsuckers and parasites that threatened to dissolve my soul.’
    • ‘MPs, councillors and all their cronies are nothing more than scroungers, spongers, parasites.’
    • ‘They were like parasites, leeching on to him, just wanting him to do this or that, or to torture him.’
    • ‘They are literary parasites, the enemies of creativity and imagination.’
    • ‘In the unionists' imagination, the rich are social parasites living lives of leisure on inherited wealth.’
    • ‘All workers were oppressed, all middle class people parasites.’
    • ‘Every governmental attempt to ameliorate poverty seems to attract its own breed of parasite and leech.’
    • ‘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.’
    hanger-on, cadger, leech, passenger, drone
    bloodsucker, sponger, sponge, scrounger, freeloader
    moocher, mooch
    View synonyms


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