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 lesson we can learn from this, is that the combination of climate change, deforestation, and the spread of opportunistic species can provide all the ingredients for a perfect storm," Van de Schootbrugge concludes.
From Science Daily ● Jul. 22, 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
Captain Jamie George had a try chalked off, his opportunistic dot-down from close range ruled out for an accidental offside.
From BBC ● Jul. 4, 2026
“When I think about the Angels right now, I just look at it as a very opportunistic time here,” Mozeliak said.
From Los Angeles Times ● Jun. 27, 2026
Later on, some people accused Blake of turning to communism for opportunistic reasons, as a way out of the prison camp.
From "Spies: The Secret Showdown Between America and Russia" by Marc Favreau
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.
