1890–95; named after J. R. Petri (died 1921), German bacteriologist
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The by-election was a petri dish that Labour had been watching closely, because if Burnham could beat Reform on that stage, it might signal that he could beat Reform in a general election.
From Slate ● Jun. 23, 2026
I’m not ashamed to admit that there have been times when those 32-ounce tubs just stare at me day after day, haloed by the refrigerator light, moving further from consumable and closer to petri dish.
From Salon ● Apr. 28, 2026
A pilot friend who is crossing the Atlantic from the Canary Islands in a sailboat this month called cruise ships a “floating petri dish.‘
From The Wall Street Journal ● Nov. 19, 2025
"How about the brain and behaviour? How can you study behaviour in a petri dish? You just can't," he says.
From BBC ● Nov. 11, 2025
After dropping each sample into a petri dish, Wilbur put bits of Henrietta’s tumor-covered cervix into containers filled with formaldehyde to save them for future use.
From "The Immortal Life of Henrietta Lacks" by Rebecca Skloot
It would soon be used quite extensively in Ohio, which became a Petri dish for Dorr’s line.
From The Wall Street Journal ● Jul. 4, 2026
A woodsy hike becomes a Petri dish of human nature in “Good One,” writer-director India Donaldson’s tense, revealing and exquisitely composed feature debut about a 17-year-old at the cusp of adulthood.
From Los Angeles Times ● Aug. 9, 2024
To stimulate the muscle cells in a more true-to-life way, Raman and her team grew cells in a Petri dish on a soft gel that contained magnetic particles.
From Science Daily ● Oct. 20, 2023
"Asylum seekers have been cooped up… for months and this inhumane treatment acts as a Petri dish for mental health issues in a cohort that are already vulnerable," he said.
From BBC ● Nov. 11, 2022
Pour the contents of a tube of liquefied agar—not inoculated—into a Petri dish to act as a control to demonstrate the sterility of the batch of agar employed.
From The Elements of Bacteriological Technique A Laboratory Guide for Medical, Dental, and Technical Students. Second Edition Rewritten and Enlarged. by Eyre, J. W. H. (John William Henry)
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.
