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parasite Syllabification: par·a·site
Pronunciation: /ˈperəˌsīt/

Definition of parasite in English:


1An organism that lives in or on another organism (its host) and benefits by deriving nutrients at the host’s expense.
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.
1.1 derogatory A person who habitually relies on or exploits others and gives nothing in return.
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.

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


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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