opportunistic
Americanadjective
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adhering to a policy of opportunism; practicing opportunism.
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Pathology.
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(of a microorganism) causing disease only under certain conditions, as when a person's immune system is impaired.
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(of a disease or infection) caused by such an organism.
Pneumocystis pneumonia is an opportunistic disease that often strikes victims of AIDS.
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adjective
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of or characterized by opportunism
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med (of an infection) caused by any microorganism that is harmless to a healthy person but debilitates a person whose immune system has been weakened by disease or drug treatment
Other Word Forms
- opportunistically adverb
- unopportunistic adjective
Etymology
Origin of opportunistic
First recorded in 1890–95; opportunist + -ic
Explanation
To be opportunistic is to quickly take advantage of a situation, usually in a way that's just plain wrong. You know how an opportunity is a chance to do something? When you're opportunistic, you take advantage of that chance, usually immediately. Most of the time, this word is not neutral: people described as opportunistic are also considered unethical, like a business taking advantage of employees or customers in an opportunistic way. If someone dropped their wallet and someone else found it and kept it, that would be opportunistic. Being opportunistic is shady and self-serving.
Vocabulary lists containing opportunistic
This Week In Culture: March 29–April 4, 2020
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“Mandatory Vaccination is Not the Answer to Measles” by Bob Sears
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This Week In Culture: October 19–25, 2019
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Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
John Davies, from the Insurance Fraud Bureau, said "opportunistic" customers were using AI to exaggerate genuine claims.
From BBC • Apr. 15, 2026
To investigate, researchers built a catalog of individual whales using opportunistic sightings and photographs contributed by the public between 2018 and 2023, along with more structured surveys conducted from 2023 to 2025.
From Science Daily • Apr. 13, 2026
Blackstone closed its Capital Opportunities Fund V, a $10 billion opportunistic credit fund, despite private credit industry turmoil.
From The Wall Street Journal • Apr. 7, 2026
Investors should watch a couple of names for opportunistic entries as the energy group pulls back.
From Barron's • Apr. 3, 2026
In most habitats, Sapiens bands fed themselves in an elastic and opportunistic fashion.
From "Sapiens: A Brief History of Humankind" by Yuval Noah Harari
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
