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.
“I think it was opportunistic and he found something that made sense to him,” Kasten said.
From Los Angeles Times ● Aug. 13, 2026
He said: "Harold's policy on the papacy may ultimately have played into the hands of his enemies, giving William's opportunistic invasion the legitimacy of a just war."
From Science Daily ● Aug. 11, 2026
Regretting using a middleman for a courier service, however opportunistic you believe the company to be, is not — on the face of it — a good enough reason to cancel the charge.
From MarketWatch ● Jul. 30, 2026
But the new administration is offering "some sort of path forward" -- touting a new peace plan, moving Suu Kyi from prison to house arrest and signing off opportunistic truces.
From Barron's ● Jul. 10, 2026
Imagine that O’Connor had written Herons are opportunistic hunters, but great blues defend a fishing hole even when it’s frozen.
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.
