parasitic
adjective
par·a·sit·ic
ˌper-ə-ˈsi-tik 
ˌpa-rə-
variants
or less commonly parasitical
ˌper-ə-ˈsi-ti-kəl
ˌpa-rə-
1
: of, relating to, or being a parasite: such as
a(1)
: living on another organism in parasitism
Some caterpillars even sport white spots that resemble the eggs of the parasitic wasps that prey upon caterpillars …—
Mary Parker Sonis
Mary Parker Sonisa parasitic yeast/plant
Filariasis, caused by parasitic worms in the human lymphatic system and carried in mosquitoes, infects some eighty million people in tropical and subtropical regions of the world.—Wayne Biddle
Wayne Biddle
(2)
: caused by or resulting from the effects of parasites
a parasitic disease/infection
(3)
of a bird
: laying eggs in the nest of another bird
The cowbird and the cuckoo are parasitic birds.
b
: exploiting the hospitality of others : depending on another or others for existence or support without making a useful or adequate return
… manipulated and glorified by self-serving, parasitic northern bureaucrats.—Edward Friedman
Edward Friedman2
phonetics
: of, relating to, or constituting a speech sound that is interposed between two other sounds usually as a by-product of transition from one place of articulation to another
The \ə\ in \ˈeləm\ for elm or in \ˈathəˌlēt\ for athlete, the \t\ in \fents\ for fence, and the \b\ and b in \ˈnimbəl\ nimble from Middle English nimel are parasitic.
parasitically
ˌper-ə-ˈsi-ti-kəl
adverb
ˌpa-rə-
During sexually quiescent phase, lampreys live simply, communally or parasitically upon other fish.
—Earl W. Count
Earl W. Count
… those who live parasitically on the political system …
—John Derbyshire
John Derbyshire
Examples of parasitic in a Sentence
Recent Examples on the Web
Endophytes can be unpredictable; for example, increasing rather than decreasing aphid infestation of beans and wheat, as noted in research from Denmark, or switching from beneficial to parasitic depending on water availability, as Hawkes witnessed.
—Anna Marija Helt, JSTOR Daily, 17 Sep. 2025
For example, since January, disease experts scattered throughout the agency have answered more than 1,500 calls from providers caring for patients with malaria, parasitic diseases, free-living amoebas, diphtheria, and botulism, according to numbers from the CDC.
—Keren Landman, The Atlantic, 17 Sep. 2025
An article from the Cornell University College of Veterinary Medicine stated that toxoplasmosis is an illness caused by a tiny parasite called Toxoplasma gondii—one of the most common parasitic diseases—which can infect nearly all warm-blooded animals, including pets and humans.
—Liz O'Connell, MSNBC Newsweek, 12 Sep. 2025
Commonly known as the brain worm, Parelaphostrongylus tenuis is a parasitic nematode that infects a large range of wild and domestic herbivores, such as moose and elk.
—Jessie Richards, The Conversation, 12 Sep. 2025
See All Example Sentences for parasitic
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Anna Marija Helt, JSTOR Daily, 17 Sep. 2025
For example, since January, disease experts scattered throughout the agency have answered more than 1,500 calls from providers caring for patients with malaria, parasitic diseases, free-living amoebas, diphtheria, and botulism, according to numbers from the CDC.
—Keren Landman, The Atlantic, 17 Sep. 2025
An article from the Cornell University College of Veterinary Medicine stated that toxoplasmosis is an illness caused by a tiny parasite called Toxoplasma gondii—one of the most common parasitic diseases—which can infect nearly all warm-blooded animals, including pets and humans.
—Liz O'Connell, MSNBC Newsweek, 12 Sep. 2025
Commonly known as the brain worm, Parelaphostrongylus tenuis is a parasitic nematode that infects a large range of wild and domestic herbivores, such as moose and elk.
—Jessie Richards, The Conversation, 12 Sep. 2025
See All Example Sentences for parasitic
Cite this Entry
“Parasitic.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/parasitic. Accessed 23 Sep. 2025.
Copy CitationMedical Definition
parasitic
1 of 2 adjective
par·a·sit·ic
ˌpar-ə-ˈsit-ik
variants
also parasitical
1
: relating to or having the habit of a parasite : living on another organism
2
: caused by or resulting from the effects of parasites
parasitic
2 of 2 nounLove words? Need even more definitions?
Merriam-Webster unabridged
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