parasite

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

Essential Meaning of parasite

1 : an animal or plant that lives in or on another animal or plant and gets food or protection from it Many diseases are caused by parasites.
2 disapproving : a person or thing that takes something from someone or something else and does not do anything to earn it or deserve it 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.

Full 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.
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Recent Examples on the Web The researchers also found the parasite was more prevalent in warmer climates and among animals with aquatic habitats. Corryn Wetzel, Smithsonian Magazine, 1 Dec. 2021 Scientists have been modeling infectious-disease outbreaks since at least the early 1900s, when the Nobel laureate Ronald Ross used mosquito-reproduction rates and parasite-incubation periods to predict the spread of malaria. New York Times, 22 Nov. 2021 The density will drop naturally, and the parasite will become less common. Ashley Stimpson, Wired, 29 Oct. 2021 This isn’t the first time the bizarre parasite has garnered attention online. Marina Pitofsky, USA TODAY, 22 Oct. 2021 But identifying and treating the parasite is a bit harder for kinky hair textures. Danielle James, Allure, 28 Dec. 2021 In director Casey Tebo's movie, the pair play employees at a toy store whose sales season turns to bloody mayhem after its customers are infected by an alien parasite. Clark Collis, EW.com, 19 Nov. 2021 Viruses are four times more likely to emerge in human populations than the average parasite (a relative risk of 400%) whereas helminths (parasitic worms) are only one fourth as likely to cause novel diseases in humans (a relative risk of only 24%). John Drake, Forbes, 28 Oct. 2021 Malaria is a complicated parasite that has evolved alongside humans for thousands of years. Sara Harrison, Wired, 15 Oct. 2021

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.

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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

Time Traveler

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 Jan 2022

Cite this Entry

“Parasite.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/parasite. Accessed 18 Jan. 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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