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

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.

parasitically

ˌper-ə-ˈsi-ti-kəl 

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

Despite a viral online claim, scientists and doctors have repeatedly said the anti-parasitic drug ivermectin is not a proven treatment. —Mary Whitfill Roeloffs, Forbes.com, 18 May 2026

Plants like cosmos, calendula, and marigolds can attract parasitic wasps and hoverflies that feed on cabbage loopers and other pests. —Lauren Landers, Better Homes & Gardens, 15 May 2026

Many insect predators such as ladybird beetles and parasitic wasps help manage pest populations naturally. —Kim Toscano, Southern Living, 13 May 2026

Ivermectin, the development of which won two researchers part of the 2015 Nobel Prize in Physiology or Medicine, is well proven for its safety and effectiveness in treating diseases caused by parasitic worms in people. —Claire Cameron, Scientific American, 12 May 2026

Word History

First Known Use

1630, in the meaning defined at sense 1

Phrases Containing parasitic

• anti-parasitic

Rhymes for parasitic

• analytic
• anxiolytic
• astrocytic
• austenitic
• catalytic
• cytolytic
• dioritic
• diphtheritic
• dolomitic
• endophytic
• epiphytic
• glauconitic

Kids Definition

parasitic

adjective

par·​a·​sit·​ic

ˌpar-ə-ˈsit-ik

: of or relating to parasites or their way of life : being a parasite

parasitically

-i-k(ə-)lē

adverb

Medical Definition

parasitic

1 of 2 adjective

par·​a·​sit·​ic ˌpar-ə-ˈsit-ik 

variants also parasitical

-i-kəl 

1

: relating to or having the habit of a parasite : living on another organism

2

: caused by or resulting from the effects of parasites

parasitically

-i-k(ə-)lē 

adverb

parasitic

2 of 2 noun

: parasiticide