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parasite Line breaks: para|site
Pronunciation: /ˈparəsʌɪt/

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
More example sentences
  • These genes are essentially immune system genes and defend the host organism from parasites.
  • After all, more than half the species on Earth are parasites, and most organisms are host to a number of them.
  • Some water molds are parasites on other organisms; they may grow on the scales or eggs of fish, or on amphibians.

Parasites exist in huge variety and include animals, plants, and micro-organisms. 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

2 derogatory A person who habitually relies on or exploits others and gives nothing in return: the capitalist is really a parasite on the workers
More example sentences
  • MPs, councillors and all their cronies are nothing more than scroungers, spongers, parasites.
  • They are literary parasites, the enemies of creativity and imagination.
  • They are all a pack of bludgers and parasites who pay no taxes but spend ours.
hanger-on, cadger, leech, passenger, drone
British informal ligger
North American informal moocher, mooch
Australian/New Zealand informal bludger


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

  • The word parasite came via Latin from Greek parasitos ‘(person) eating at another's table’, from para- ‘alongside’ and sitos ‘food’, and originally came into the language as a term for a hanger-on or sponger. Its use as a term in biology dates from the early 18th century.

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