par·​a·​sit·​ic | \ ˌper-ə-ˈsi-tik How to pronounce parasitic (audio) , ˌpa-rə- \
variants: or less commonly parasitical \ ˌper-​ə-​ˈsi-​ti-​kəl How to pronounce parasitic (audio) , ˌpa-​rə-​ \

Definition of parasitic

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 a 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
(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
2 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.

Other Words from parasitic

parasitically \ ˌper-​ə-​ˈsi-​ti-​kəl How to pronounce parasitic (audio) , ˌpa-​rə-​ \ adverb
During sexually quiescent phase, lampreys live simply, communally or parasitically upon other fish. — Earl W. Count … those who live parasitically on the political system … — John Derbyshire

Examples of parasitic in a Sentence

Recent Examples on the Web It's approved to treat some parasitic worms, head lice and skin conditions, but isn't an antiviral drug. Ron Wood, Arkansas Online, 9 May 2022 In the lab, each fish undergoes a full physical, inside and out, first for sea lice attached to the animal’s skin and then for parasitic worms in its organs and gills. Rachel Nuwer, Scientific American, 28 Apr. 2022 Doctors had treated him for several days with a high dose of glucocorticoid, which suppresses some immune responses—and creates prime conditions for parasitic worms to flourish. Beth Mole, Ars Technica, 22 Apr. 2022 Researchers suspect a link between rat poisons and mange, a parasitic skin disease that causes crusting and lesions and has contributed to the deaths of scores of bobcats and coyotes. Nathan Solis, Los Angeles Times, 10 Mar. 2022 The Food and Drug Administration has approved ivermectin for use by people and animals for some parasitic worms, head lice and skin conditions. From Usa Today Network And Wire Reports, USA TODAY, 15 Apr. 2022 Nevertheless, the boat is remarkably well preserved — a fact attributable, experts speculate, to the absence from cold Antarctic waters of wood-eating creatures like parasitic worms. Jody Rosen, New York Times, 30 Mar. 2022 Huffman theorized that the chimpanzees were consuming bunches of these leaves in order to expel parasitic worms. Maddie Bender, Wired, 8 Mar. 2022 It's approved to treat some parasitic worms, head lice and skin conditions, but isn't an antiviral drug. Tom Sissom, Arkansas Online, 18 Feb. 2022 See More

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

First Known Use of parasitic

1630, in the meaning defined at sense 1

Learn More About parasitic

Time Traveler for parasitic

Time Traveler

The first known use of parasitic was in 1630

See more words from the same year

Dictionary Entries Near parasitic



parasitic castration

See More Nearby Entries 

Statistics for parasitic

Last Updated

15 May 2022

Cite this Entry

“Parasitic.” Dictionary, Merriam-Webster, Accessed 23 May. 2022.

Style: MLA
MLACheck Mark Icon ChicagoCheck Mark Icon APACheck Mark Icon Merriam-WebsterCheck Mark Icon

More Definitions for parasitic


par·​a·​sit·​ic | \ ˌper-ə-ˈsi-tik \

Kids Definition of parasitic

: relating to or having the habit of a parasite : caused by parasites a parasitic worm parasitic diseases


par·​a·​sit·​ic | \ ˌpar-ə-ˈsit-ik How to pronounce parasitic (audio) \
variants: also parasitical \ -​i-​kəl How to pronounce parasitic (audio) \

Medical Definition of parasitic

 (Entry 1 of 2)

1 : relating to or having the habit of a parasite : living on another organism
2 : caused by or resulting from the effects of parasites

Other Words from parasitic

parasitically \ -​i-​k(ə-​)lē How to pronounce parasitic (audio) \ adverb



Medical Definition of parasitic (Entry 2 of 2)


Test Your Vocabulary

Name That Food

  • a-light
  • Name these cookies!
Spell It

Can you spell these 10 commonly misspelled words?

Universal Daily Crossword

A daily challenge for crossword fanatics.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!