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
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.
The most likely form of opportunistic aggression isn’t a large-scale invasion or blockade of Taiwan, but smaller-scale activities.
From The Wall Street Journal • May 21, 2026
But as long as the war remains reasonably limited in duration and doesn’t involve the commitment of large numbers of ground troops, opportunistic aggression against Taiwan as a function of Operation Epic Fury is unlikely.
From The Wall Street Journal • May 21, 2026
Analysts at 22V Research see the Aragchi visit as an opportunistic move by Beijing to signal it could nudge each side to a compromise,
From Barron's • May 6, 2026
"We will not submit to opportunistic lawyers looking to manufacture a payday from us," they added.
From BBC • Apr. 23, 2026
And their ability to eat nonfishy meals is, in turn, an elaboration of their being opportunistic hunters.
From "The Sense of Style" by Steven Pinker
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.
