parasite

noun
par·​a·​site | \ ˈper-ə-ˌsīt How to pronounce parasite (audio) , ˈpa-rə- \
plural parasites

Definition of parasite

1 : an organism living in, on, or with another organism in order to obtain nutrients, grow, or multiply often in a state that directly or indirectly harms the host (see host entry 3 sense 2a) Now the death of its host is certainly a setback to any parasite. To some (like the tapeworm) it is fatal; but smarter ones (like the louse) simply go off in search of a new host.— David Jones The fungus is an obligate parasite, that is, it must have a living host (tobacco) on which to grow and complete its life cycle.— G. B. Lucas The blood schizogonic cycle of human malaria parasites has thus far been the most exhaustively studied phase of parasite development.— Dominique Mazier et al. Sadly, the vireo is vulnerable to a nest parasite, the brown-headed cowbird … . The cowbird lays its much-larger eggs in the vireo's nest, which hatch first and place such a high food demand on its tiny "parents" that the vireo young go unfed.— Karen D. Fishler

Note: Some restrict the use of parasite to include only multicellular forms (such as protozoans and helminths) while others use it to include bacteria and viruses.

Unlike bacteria or viruses, parasites undergo a metamorphosis during their life cycles that presents the human immune system with a moving target.— Lawrence M. Fisher Like all viruses, the human immunodeficiency virus (HIV) is an intracellular parasite: the virus particle itself is inert and cannot propagate or do any damage until it enters a host cell.— Jonathan N. Weber and Robin A. Weiss Salmonella species are intracellular parasites, and it is thought that these bacteria gain access to their host by penetrating through intestinal epithelial cells.— B. Brett Finlay et al. — see also ectoparasite, endoparasite
2 : someone or something that resembles a biological parasite in living off of, being dependent on, or exploiting another while giving little or nothing in return But the frequent and familiar companions of the great, are those parasites, who practise the most useful of all arts, the art of flattery …— Edward Gibbon Their lyrics … convey a bilious contempt for the city's wealthy parasites— Philip Montoro In their view, the country is afflicted with a class of parasites—"Career politicians," who devote their lives to perpetuating themselves in office by spending the people's money.— Hendrick Hertzberg Regulatory agencies have stripped Holyfield of his boxing license now, protecting him from his pride and from the parasites who can still squeeze money out of the faded neon in his name.— Dan Le Batard

Choose the Right Synonym for parasite

parasite, sycophant, toady, leech, sponge mean a usually obsequious flatterer or self-seeker. parasite applies to one who clings to a person of wealth, power, or influence or is useless to society. a jet-setter with an entourage of parasites sycophant adds to this a strong suggestion of fawning, flattery, or adulation. a powerful prince surrounded by sycophants toady emphasizes the servility and snobbery of the self-seeker. cultivated leaders of society and became their toady leech stresses persistence in clinging to or bleeding another for one's own advantage. a leech living off his family and friends sponge stresses the parasitic laziness, dependence, and opportunism of the cadger. a shiftless sponge, always looking for a handout

Examples of parasite in a Sentence

Many diseases are caused by parasites. She's a parasite who only stays with him for the money. These new companies are parasites feeding off the success of those who spent the last decade establishing the industry.
Recent Examples on the Web LeBrun and Plowes found that those bodies contained spores of a parasite from the fungal microsporidian group. Jennifer Ouellette, Ars Technica, 28 Mar. 2022 Another is to proactively treat everyone in a community with Mectizan, to disrupt the life cycle of the parasite. Sarah Ferguson, Forbes, 30 Jan. 2022 Mute swans examined by USGS had fatal infections of the intestinal parasite, according to a DNR news release. Carrie Napoleon, chicagotribune.com, 28 Dec. 2021 The transposons might then be the engines driving horizontal gene transfers that the parasite needs to survive. Quanta Magazine, 21 Apr. 2021 The parasite cannot survive in cooked fish, officials said. Lauren Hernández, San Francisco Chronicle, 13 Apr. 2022 People can ingest the parasite while consuming water or fresh produce contaminated with Cyclospora, like these Ocean Mist Romaine Hearts lettuce. Chris Smith, BGR, 11 Apr. 2022 Plants engineered to evade SAP05 had notably shorter lives when they were infected by the parasite. New York Times, 1 Oct. 2021 Universal Television Alternative Studio temporarily stopped production June 2 on the Los Angeles set after a crew member tested positive for giardia, a parasite that can cause intestinal ailments, including diarrhea, in humans. Bill Keveney, USA TODAY, 7 Aug. 2021 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'parasite.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of parasite

1539, in the meaning defined at sense 1

History and Etymology for parasite

Middle French, from Latin parasitus, from Greek parasitos, from para- + sitos grain, food

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Time Traveler for parasite

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The first known use of parasite was in 1539

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Dictionary Entries Near parasite

parasitary

parasite

parasite drag

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Last Updated

14 May 2022

Cite this Entry

“Parasite.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/parasite. Accessed 17 May. 2022.

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More Definitions for parasite

parasite

noun
par·​a·​site | \ ˈper-ə-ˌsīt How to pronounce parasite (audio) \

Kids Definition of parasite

1 : a living thing (as a flea, worm, or fungus) that lives in or on another living thing and gets food and sometimes shelter from it and usually causes harm to it
2 : a person who lives at the expense of another

parasite

noun
par·​a·​site | \ ˈpar-ə-ˌsīt How to pronounce parasite (audio) \

Medical Definition of parasite

: an organism living in, with, or on another organism in order to obtain nutrients, grow, or multiply often in a state that directly or indirectly harms the host (see host sense 1) The blood schizogonic cycle of human malaria parasites has thus far been the most exhaustively studied phase of parasite development.— Dominique Mazier et al., Nature

Note: Some restrict the use of parasite to include only multicellular forms (such as protozoans and helminths) while others use it to include bacteria and viruses.

These cells call up a portion of the immune system that identifies and destroys cells infected with bacteria, viruses, and parasites.— L. Seachrist, Science News Like all viruses, the human immunodeficiency virus (HIV) is an intracellular parasite: the virus particle itself is inert and cannot propagate or do any damage until it enters a host cell.— Jonathan N. Weber and Robin A. Weiss, Scientific American Salmonella species are intracellular parasites, and it is thought that these bacteria gain access to their host by penetrating through intestinal epithelial cells.— B. Brett Finlay et al., Science

More from Merriam-Webster on parasite

Nglish: Translation of parasite for Spanish Speakers

Britannica English: Translation of parasite for Arabic Speakers

Britannica.com: Encyclopedia article about parasite

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