parasite
noun
par·a·site
ˈper-ə-ˌsīt 
ˈpa-rə-
plural parasites
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 1 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
David JonesThe 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
G. B. LucasThe blood schizogonic cycle of human malaria parasites has thus far been the most exhaustively studied phase of parasite development.—Dominique Mazier et al.
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
Karen D. FishlerNote: 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
Lawrence M. FisherLike 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
Jonathan N. Weber and Robin A. WeissSalmonella 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
B. Brett Finlay et al.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
Edward GibbonTheir lyrics … convey a bilious contempt for the city's wealthy parasites …—Philip Montoro
Philip MontoroIn 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
Hendrick HertzbergRegulatory 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
Dan Le BatardSynonyms
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
Indoor cats are also less at risk from contagious diseases and parasites.
—Rachael O'Connor, Newsweek, 4 Nov. 2024
There’s a myth that pumpkin seeds act as a natural dewormer for dogs with parasites, but Watkins says that’s not the case.
—Clare Mulroy, USA TODAY, 31 Oct. 2024
Keep your pet’s vaccines and worming medications up-to-date since they can be exposed to rabies, canine distemper and other parasites from raccoons and their waste.
—Arricca Elin Sansone, Southern Living, 31 Oct. 2024
If a parasite causes the infection, the incubation time can be one to two weeks.
—Maxine Lipner, Verywell Health, 30 Oct. 2024
See all Example Sentences for parasite 
Examples are automatically compiled from online sources to
show current usage.
Read More
Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
Send us feedback.
Rachael O'Connor, Newsweek, 4 Nov. 2024
There’s a myth that pumpkin seeds act as a natural dewormer for dogs with parasites, but Watkins says that’s not the case.
—Clare Mulroy, USA TODAY, 31 Oct. 2024
Keep your pet’s vaccines and worming medications up-to-date since they can be exposed to rabies, canine distemper and other parasites from raccoons and their waste.
—Arricca Elin Sansone, Southern Living, 31 Oct. 2024
If a parasite causes the infection, the incubation time can be one to two weeks.
—Maxine Lipner, Verywell Health, 30 Oct. 2024
See all Example Sentences for parasite
Dictionary Entries Near parasite
Cite this Entry
“Parasite.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/parasite. Accessed 26 Nov. 2024.
Copy CitationKids Definition
parasite
noun
par·a·site
ˈpar-ə-ˌsīt
1
: a person who lives at the expense of another
2
: a living thing which lives in or on another living thing in parasitism
3
: a person dependent on something else for life or support without making proper return
Medical Definition
parasite
noun
par·a·site
ˈpar-ə-ˌsīt
: 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
Dominique Mazier et al., NatureNote: 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
L. Seachrist, Science NewsLike 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
Jonathan N. Weber and Robin A. Weiss, Scientific AmericanSalmonella 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
B. Brett Finlay et al., ScienceLove words? Need even more definitions?
Merriam-Webster unabridged
Share